physioglove_slide_presentation

The “PhysioGlove”®, a New Diagnostic 12-Lead ECG Acquisition Device: Assessment of Reproducibility and Diagnostic Accuracy Compared to ECGs Acquired Using the Conventional ECG Cable Michael Luc, Roberto M. Lang, Dan Tzivoni, Roderick Childers, Morton Arnsdorf, Irving Levi, Daniel David, University of Chicago, Chicago, IL, Tel Aviv University, Tel Aviv, Israel

RARALALA

V3V4V5V6

The “PhysioGlove”The “PhysioGlove”

OBJECTIVES:OBJECTIVES:

1.1. Definition of Definition of ECG Waveform ReproducibilityECG Waveform Reproducibility of the of the “PhysioGlove” (PG) compared to the Regular ECG “PhysioGlove” (PG) compared to the Regular ECG Cable (RC).Cable (RC).

1.1. Definition of the Definition of the Diagnostic AccuracyDiagnostic Accuracy of a 12 lead of a 12 lead ECG obtained using the “PhysioGlove’ to that ECG obtained using the “PhysioGlove’ to that obtained using a Regular Cable, in the same patient.obtained using a Regular Cable, in the same patient.

3. Definition of the appropriate 3. Definition of the appropriate Anthropomorphic Anthropomorphic BoundariesBoundaries for the “PhysioGlove” for the “PhysioGlove” ..

PATIENT POPULATIONPATIENT POPULATION::

A random population (regardless of gender, age, race A random population (regardless of gender, age, race anthropomorphismanthropomorphism etc.) of adult consenting patients etc.) of adult consenting patients attending a routine visit at the cardiology outpatient attending a routine visit at the cardiology outpatient clinics of the University of Chicago Medical Center, clinics of the University of Chicago Medical Center, Chicago, Ill. and the Shaare Zedek Medical Center, Chicago, Ill. and the Shaare Zedek Medical Center, Jerusalem, Israel. Jerusalem, Israel.

These clinics serve a population that seem to represent These clinics serve a population that seem to represent a mixed international population in terms of gender a mixed international population in terms of gender age race, anthropomorphism and clinical pathologies.age race, anthropomorphism and clinical pathologies.

PROTOCOL:

Patients signed an informed consent form.Height, weight, chest circumference and clinical data were recorded.Each patient had the following successive ECG recordings:

1. A “PhysioGlove” ECG.

2. A Regular Cable ECG with the chest electrodes positioned in the exact locations as the “PhysioGlove”.

3. A Regular Cable ECG with chest electrodes located at the correct anatomical location as per convention.

All ECG tracings were digitally recorded, labeled and stored in the “PhysioGlove ES-1” ECG systems database.

Analysis and comparisons were made using a well established computerized ECG analysis software.

RESULTS:RESULTS:Analysis included 181/321 patients

F/M: 72/109Age range: 21-83 yearsRace: ~ 50% AA the rest Cauc. Hisp. Asian.25 where volunteering medical students (normal control)The rest had a wide range of CV & other pathologies.

Patients were divided into three groups according to chest circumference (CC):

Small: CC < 85cm. N= 5Medium + Large: CC - 85 -108cm. N= 163Extra Large: CC > 108cm. N= 13

Patient Distribution According to Chest Circumference (n=321)

Chest Circumference (cm)

86cm. = 33.9" 118cm. = 46.5"

285/321 patients = 86%86%

102cm = 40.1”102cm = 40.1”

Heart Rate - 78Heart Rate - 78Axis : QRS - -13, Axis : QRS - -13, Duration : QRS - 138, ST - 52, Duration : QRS - 138, ST - 52, P - 108P - 108Interval : PR - 178, QT - 420, Interval : PR - 178, QT - 420, QTc - 451QTc - 451

Interpretation :Interpretation :Sinus rhythm Sinus rhythm Left bundle branch blockLeft bundle branch blockPossible lateral infarct - age Possible lateral infarct - age undeterminedundetermined

Summary : Abnormal ECGSummary : Abnormal ECG

Interpretation :Interpretation :Sinus rhythmSinus rhythmLeft bundle branch blockLeft bundle branch blockPossible lateral infarct - age Possible lateral infarct - age undeterminedundetermined

PhysioGlove Standard Cable

ECG Reproducibility Near MatchNear Match

Interpretation :Interpretation :Sinus rhythm Sinus rhythm Possible left atrial abnormalityPossible left atrial abnormalityLeft ventricular hypertrophyLeft ventricular hypertrophyPossible right ventricular Possible right ventricular hypertrophyhypertrophyInferior/lateral ST-T Inferior/lateral ST-T abnormality may be due to abnormality may be due to hypertrophy and/or ischemiahypertrophy and/or ischemia

Interpretation :Interpretation :Sinus rhythmSinus rhythmPossible left atrial abnormalityPossible left atrial abnormalityLeft ventricular hypertrophyLeft ventricular hypertrophyPossible right ventricular Possible right ventricular hypertrophyhypertrophyInferior/lateral T abnormality Inferior/lateral T abnormality may be due to hypertrophy may be due to hypertrophy and/or ischemiaand/or ischemia

ECG Reproducibility

ECG MatchECG Match

Heart Rate - 68Heart Rate - 68Axis : QRS - 58Axis : QRS - 58Duration : QRS - 94, ST - 72, Duration : QRS - 94, ST - 72, P - 122P - 122Interval : PR - 176, QT - 386, Interval : PR - 176, QT - 386, QTc - 400QTc - 400

Interpretation :Interpretation :Sinus rhythm Sinus rhythm

Summary : Normal ECGSummary : Normal ECG

ECG Reproducibility Signif.Signif. Mismatch (L-I; L-3; AVLMismatch (L-I; L-3; AVL

157157 87%87%87%87%6969

86%86% ECG MatchECG Match

ECG Near MatchECG Near Match

Signif. ECG MismatchSignif. ECG Mismatch

TOTALTOTAL

8%8%1515

99 5%5%

100%100%181181

9%9% 77

33 4%4%

7979 44%44%

Anatomic Anatomic CorrectionCorrection

88 8%8%

66 6%6%

102102 56%56%

No Anatomic No Anatomic CorrectionCorrection

TOTALTOTAL

95%95%

ECG Waveform Reproducibility: All Study patients (n=181)

Exact Diagnosis.Exact Diagnosis.

Minor Diagnostic ChangesMinor Diagnostic Changes

Significant Diagnostic MismatchSignificant Diagnostic Mismatch

9696 94%94%

(5/6 pacemaker patients)(5/6 pacemaker patients)

Diagnostic Accuracy: Patients with no need for Anatomic Correction (n=102)

SUMMARY and CONCLUSIONS:

• The ECG recordings obtained by the “PhysioGlove” provide both very high waveform reproducibility (95%) as well as diagnostic accuracy (94%-96%).

• As predicted by past, large scale, anthropomorphic population studies, about 85%-90% of a typical adult population has a mean chest circumference of 40”.

• The single size “PhysioGlove”, used in this study, was designed to fit this population range.• In this study’s population, 86% had a CC ranging between 34” and 46” with a mean CC of 40.1”. • Despite the need for minor anatomic corrections in 44% of the study population the overall

diagnostic accuracy of the single size “PhysioGlove” was 94%-96%.• These results indicate that the “PhysioGlove” will become a highly important tool in significantly

improving the reproducibility an diagnostic accuracy of present day diagnostic 12 lead electrocardiography.

• Furthermore, the potential for ambulatory self-use of the “PhysioGlove” by the patients themselves opens new venues for accurate early detection of acute myocardial ischemia, thereby significantly shortening the time from initiation of symptoms to reperfusion.

ECG Unchanged

ECG Changed +/-

53 (96%)53 (96%)6 (11%)6 (11%)

49 (89%)49 (89%)

4 (19%)4 (19%) 33

Signif. Change

Minor Change

Signif. Change

Minor Change

20 (95%)20 (95%)

17 (81%)17 (81%)

Diag. Changed

Diag. Unchanged

Diag. Changed

Diag. Unchanged

Diag. Changed

Diag. Unchanged

ECG Changed

Diagnostic Accuracy: Patients with need for Anatomic Correction (n=79)

RATIONAL - II

The Same document stresses the following:

• PresentlyPresently Lead Switches Lead Switches andand Lead Misplacements Lead Misplacements still lead to poor reproducibility poor reproducibility and and considerable variability of the ECGvariability of the ECG ..

• Electrode placement accuracy during routine ECG Electrode placement accuracy during routine ECG recording has decreased further with time.recording has decreased further with time.

Theses major problems can be solved by either:

1. The strict restriction of the ECG recording to highly trained, diligent personnel, a whish that has not materialized in the last 100 years.

2. Creation of a “fool proof” 12 lead ECG recording system, the “PhysioGlove”, that will, by and large, allow almost anybody, including the patients themselves, to record an accurate and reproducible ECG.

(Circulation. 2007;115:1306-1324.)

RATIONAL - I

The joint scientific statement by the AHA/ACC and the Heart Rhythm Society on the standardization and interpretation of the Electrocardiogram states the following:

“In the century since the introduction of the string galvanometer by Willem Einthoven, the electrocardiogram (ECG) has become the most commonly conducted cardiovascular diagnostic procedure and a fundamental tool of clinical practice”

“Because of its broad applicability, the accurate Because of its broad applicability, the accurate recording and precise interpretation of the ECG are recording and precise interpretation of the ECG are critical”.critical”.

“The establishment of and adherence to professionallydeveloped and endorsed evidence-based standards for all phases of the ECG procedure is an important step in ensuring the high level of precision required and expected by clinicians and their patients”.

(Circulation. 2007;115:1306-1324.)

ABSTRACT

BACKGROUND: Presently12 lead ECG still lacks in reproducibility (R) and diagnostic accuracy (DA). The PhysioGlove® (PG), a new ECG acquisition device incorporates all 10 electrodes in a glove placed on the left hand (Fig), for rapid (no lead wires, no skin preping), accurate & reproducible ECG recording with minimal proficiency. METHODS: To compare R and DA of PG-ECGs with regular ECG cable (RC) ECGs, 207 consecutive, consenting adult cardiology outpatients (pts) were studied. Height, weight, chest circumference (CC) and diagnoses were noted. The PG was carefully designed (using modeling and extensive anthropomorphic population studies) to fit >80% of a random adult US population. All pts had three ECG’s. ECG-I= using the PG, ECG-II= using a RC with chest electrodes (CE’s) positioned in the exact location of the PG CE’s, ECG-III= placing the RC-CE’s in the conventional anatomic locations. ECG-I & II were compared to asses R, ECG-I & III were compared to assess DA. Automatic ECG analysis was used for comparisons. RESULTS: M/F ratio: 123/84, ages: 21-88y, >50% of African American origin, height range 57-76”, weight 102-320lb. CC range 31”-52”. Overall R was 95% (regardless of anthropomorphism). In pts with CC range 34”-46” (n=184/207 = 89%) DA was 96.8%. In pts with CC>46” DA was 91.8%. CONCLUSIONS: The PG showed excellent R regardless of anthropomorphism. The PG DA was 96.8% in almost 90% of a representative US cardiology outpatient clinic population, significantly exceeding the published conventional ECG R and DA.

ACC 2008 Abstract

RARALALA

V3V4V5V6

The “The “PhysioGlovePhysioGlove””

RATIONAL - I

The Joint Scientific Statement by the AHA/ACC and the Heart Rhythm Society on the Standardization and Interpretation of the Electrocardiogram states the following:

“In the century since the introduction of the string galvanometer by Willem Einthoven, the electrocardiogram (ECG) has become the most commonly conducted cardiovascular diagnostic procedure and a fundamental tool of clinical practice” “Because of its broad applicability, the accurate recording and precise Because of its broad applicability, the accurate recording and precise interpretation of the ECG are critical”.interpretation of the ECG are critical”.

“The establishment of and adherence to professionallydeveloped and endorsed evidence-based standards for all phases of the ECG procedure is an important step in ensuring the high level of precision required and expected by clinicians and their patients”.

(Circulation. 2007;115:1306-1324.)

RATIONAL - II

The Same document stresses the following:

•PresentlyPresently Lead Switches Lead Switches andand Lead Misplacements Lead Misplacements still lead to poor poor reproducibility reproducibility and and considerable variability of the ECGvariability of the ECG..

•Electrode placement accuracy during routine ECG recording has Electrode placement accuracy during routine ECG recording has decreased further with time.decreased further with time.

Theses major problems can be solved by either:

1. The strict restriction of the ECG recording to highly trained, diligent personnel, a whish that has not materialized in the last 100 years.

2. Creation of a “fool proof” 12 lead ECG recording system, the “PhysioGlove”, that will, by and large, allow almost anybody, including the patients themselves, to record an accurate and reproducible ECG.

(Circulation. 2007;115:1306-1324.)

The “PhysioGlove”The “PhysioGlove”

• No Lead WiresNo Lead Wires• No TrainingNo Training• No Special Skin Prep.No Special Skin Prep.•

RARALALA

V3V4V5V6

PhysioGlove - EsPhysioGlove - Es

OBJECTIVES:OBJECTIVES:

1.1. Definition of Definition of ECG Waveform ReproducibilityECG Waveform Reproducibility of the “PhysioGlove” of the “PhysioGlove” (PG) compared to the Regular ECG Cable (RC).(PG) compared to the Regular ECG Cable (RC).

1.1. Definition of the Definition of the Diagnostic AccuracyDiagnostic Accuracy of a 12 lead ECG obtained of a 12 lead ECG obtained using the “PhysioGlove’ to that obtained using a Regular Cable, in the using the “PhysioGlove’ to that obtained using a Regular Cable, in the same patient.same patient.

3. Definition of the appropriate 3. Definition of the appropriate Anthropomorphic BoundariesAnthropomorphic Boundaries for the for the “PhysioGlove”.“PhysioGlove”.

PATIENT POPULATIONPATIENT POPULATION::

A random population (regardless of gender, age, race A random population (regardless of gender, age, race anthropomorphismanthropomorphism etc.) of adult consenting patients attending a etc.) of adult consenting patients attending a routine visit at the cardiology outpatient clinics of the University of routine visit at the cardiology outpatient clinics of the University of Chicago Medical Center, Chicago, Ill. and the Shaare Zedek Medical Chicago Medical Center, Chicago, Ill. and the Shaare Zedek Medical Center, Jerusalem, Israel. Center, Jerusalem, Israel.

These clinics serve a population that seem to represent a mixed These clinics serve a population that seem to represent a mixed international population in terms of gender age race, international population in terms of gender age race, anthropomorphism and clinical pathologies.anthropomorphism and clinical pathologies.

PROTOCOL:

Patients signed an informed consent form.Height, weight, chest circumference and clinical data were recorded.Each patient had the following successive ECG recordings:

1. A “PhysioGlove” ECG.

2. A Regular Cable ECG with the chest electrodes positioned in the exact locations as the “PhysioGlove”.

3. A Regular Cable ECG with chest electrodes located at the correct anatomical location as per convention.

All ECG tracings were digitally recorded, labeled and stored in the “PhysioGlove ES-1” ECG systems database.

Analysis and comparisons were made using a well established computerized ECG analysis software.

RESULTS:RESULTS:Analysis included 181/321 patients

F/M: 72/109Age range: 21-83 yearsRace: ~ 50% AA the rest Cauc. Hisp. Asian.25 where volunteering medical students (normal control)The rest had a wide range of CV & other pathologies.

Patients were divided into three groups according to chest circumference (CC):

Small: CC < 85cm. N= 5Medium + Large: CC - 85 -108cm. N= 163Extra Large: CC > 118cm. N= 13

Patient Distribution According to Chest Circumference (n=321)

Chest Circumference (cm)

102cm = 40.1”102cm = 40.1”

86cm. = 33.9" 118cm. = 46.5"

285/321 patients = 86%86%

Heart Rate - 69Heart Rate - 69Axis : QRS - -13, Axis : QRS - -13, Duration : QRS - 106, ST - 126, Duration : QRS - 106, ST - 126, P - 134 P - 134Interval : PR - 166, QT - 434, Interval : PR - 166, QT - 434, QTc - 449QTc - 449

Interpretation :Interpretation :Sinus rhythm Sinus rhythm Possible left atrial abnormalityPossible left atrial abnormalityLeft ventricular hypertrophyLeft ventricular hypertrophyPossible right ventricular Possible right ventricular hypertrophyhypertrophyInferior/lateral ST-T Inferior/lateral ST-T abnormality may be due to abnormality may be due to hypertrophy and/or ischemiahypertrophy and/or ischemia

Heart Rate - 70Heart Rate - 70Axis : QRS - -10, Axis : QRS - -10, Duration : QRS - 102, ST - 140, Duration : QRS - 102, ST - 140, P - 134 P - 134Interval : PR - 168, QT - 434, Interval : PR - 168, QT - 434, QTc - 451QTc - 451

Interpretation :Interpretation :Sinus rhythmSinus rhythmPossible left atrial abnormalityPossible left atrial abnormalityLeft ventricular hypertrophyLeft ventricular hypertrophyPossible right ventricular Possible right ventricular hypertrophyhypertrophyInferior/lateral T abnormality Inferior/lateral T abnormality may be due to hypertrophy may be due to hypertrophy and/or ischemiaand/or ischemia

ECG Reproducibility

ECG MatchECG Match

Interpretation :Interpretation :Sinus rhythm Sinus rhythm Left bundle branch blockLeft bundle branch blockPossible lateral infarct - age Possible lateral infarct - age undeterminedundetermined

Heart Rate - 89Heart Rate - 89Axis : QRS - -16, Axis : QRS - -16, Duration : QRS - 144, ST - Duration : QRS - 144, ST - 74, P - 10674, P - 106Interval : PR - 170, QT - 402, Interval : PR - 170, QT - 402, QTc - 452QTc - 452

Interpretation :Interpretation :Sinus rhythmSinus rhythmLeft bundle branch blockLeft bundle branch blockPossible lateral infarct - age Possible lateral infarct - age undeterminedundetermined

ECG Reproducibility Near MatchNear Match

ECG Reproducibility

Signif.Signif. Mismatch (L-I; L-3; AVLMismatch (L-I; L-3; AVL

Anatomic Anatomic CorrectionCorrection

No Anatomic No Anatomic CorrectionCorrection TOTALTOTAL

157157 87%87%87%87%6969

86%86% ECG MatchECG Match

ECG Near MatchECG Near Match

Signif. ECG MismatchSignif. ECG Mismatch

TOTALTOTAL

8%8%1515

99 5%5%

100%100%181181

9%9% 77

33 4%4%

7979 44%44%

88 8%8%

66 6%6%

102102 56%56%

95%95%

ECG Waveform Reproducibility: All Study patients (n=181)

Exact Diagnosis.Exact Diagnosis.

Minor Diagnostic ChangesMinor Diagnostic Changes

Significant Diagnostic MismatchSignificant Diagnostic Mismatch

96 =96 = 94%94%

(5/6 pacemaker patients)(5/6 pacemaker patients)

Diagnostic Accuracy: Patients with no need for anatomic correction (n=102)

ECG Unchanged

53 (96%)53 (96%)

6 (11%)6 (11%)

49 (89%)49 (89%)

4 (19%)4 (19%)

17 (81%)17 (81%)

Diag. Changed

Diag. Unchanged

Diag. Changed

Diag. Unchanged

ECG Changed

Signif. Change

Minor Change

20 (95%)20 (95%)

Signif. Change

Minor Change

ECG Changed +/-

Diag. Changed

Diag. Unchanged

SUMMARY and CONCLUSIONS I :

• The ECG recordings obtained by the “PhysioGlove” provide both very high waveform reproducibility (95%) as well as diagnostic accuracy (94%-96%).

• As predicted by past, large scale, anthropomorphic population studies, about 85%-90% of a typical adult population has a mean chest circumference of 40”.

• The single size “PhysioGlove”, used in this study, was designed to fit this population range.

• In this study’s population, 86% had a CC ranging between 34” and 46” with a mean CC of 40.1”.

SUMMARY and CONCLUSIONS II:

•Despite the need for minor anatomic corrections in 44% of the study population the overall diagnostic accuracy of the single size “PhysioGlove” was 94%-96%.

• These results indicate that the “PhysioGlove” will become a highly important tool in significantly improving the reproducibility and diagnostic accuracy of present day diagnostic 12 lead electrocardiography.

• Furthermore, the potential for ambulatory self-use of the “PhysioGlove” by the patients themselves opens new venues for accurate early detection of acute myocardial ischemia, thereby significantly shortening the time from initiation of symptoms to reperfusion.

The “PhysioGlove”®, a New Diagnostic 12 Lead ECG Acquisition Device: Assessment of Reproducibility and Diagnostic Accuracy Compared to ECGs Acquired Using the Conventional ECG Cable

Michael Luc, Roberto M. Lang, Dan Tzivoni, Roderic Childers, Morton Arnsdorf, Irving Levi, Daniel David, University of Chicago, Il, Tel Aviv University, Hebrew University, Israel.

Background: Presently12 lead ECG still lacks in reproducibility (R) and diagnostic accuracy (DA). The PhysioGlove® (PG), a new ECG acquisition device incorporates all 10 electrodes in a glove placed on the left hand (Fig), for rapid (no lead wires, no skin preping), accurate & reproducible ECG recording with minimal proficiency.

Methods: To compare R and DA of PG-ECGs with regular ECG cable (RC) ECGs, 207 consecutive, consenting adult cardiology outpatients (pts) were studied. Height, weight, chest circumference (CC) and diagnoses were noted. The PG was carefully designed (using modeling and extensive anthropomorphic population studies) to fit >80% of a random adult US population. All pts had three ECG’s. ECG-I= using the PG, ECG-II= using a RC with chest electrodes (CE’s) positioned in the exact location of the PG CE’s, ECG-III= placing the RC-CE’s in the conventional anatomic locations. ECG-I & II were compared to asses R, ECG-I & III were compared to assess DA. Automatic ECG analysis was used for comparisons. Results: M/F ratio: 123/84, ages: 21-88y, >50% of African American origin, height range 57-76”, weight 102-320lb. CC range 31”-52”. Overall R was 95% (regardless of anthropomorphism). In pts with CC range 34”-46” (n=184/207 = 89%) DA was 96.8%. In pts with CC>46” DA was 91.8%. Conclusions: The PG showed excellent R regardless of anthropomorphism. The PG DA was 96.8% in almost 90% of a representative US cardiology outpatient clinic population, significantly exceeding the published conventional ECG R and DA.

The “PhysioGlove”®, a New Diagnostic 12 Lead ECG Acquisition Device: Assessment of Reproducibility and Diagnostic Accuracy Compared to ECGs Acquired Using the Conventional ECG Cable Michael Luc, Roberto M. Lang, Dan Tzivoni, Roderic Childers, Morton Arnsdorf, Irving Levi, Daniel David, University of Chicago, Il, Tel Aviv University, Hebrew University, Israel.Background: Presently12 lead ECG still lacks in reproducibility (R) and diagnostic accuracy (DA). The PhysioGlove® (PG), a new ECG acquisition device incorporates all 10 electrodes in a glove placed on the left hand (Fig), for rapid (no lead wires, no skin preping), accurate & reproducible ECG recording with minimal proficiency. Methods: To compare R and DA of PG-ECGs with regular ECG cable (RC) ECGs, 207 consecutive, consenting adult cardiology outpatients (pts) were studied. Height, weight, chest circumference (CC) and diagnoses were noted. The PG was carefully designed (using modeling and extensive anthropomorphic population studies) to fit >80% of a random adult US population. All pts had three ECG’s. ECG-I= using the PG, ECG-II= using a RC with chest electrodes (CE’s) positioned in the exact location of the PG CE’s, ECG-III= placing the RC-CE’s in the conventional anatomic locations. ECG-I & II were compared to asses R, ECG-I & III were compared to assess DA. Automatic ECG analysis was used for comparisons. Results: M/F ratio: 123/84, ages: 21-88y, >50% of African American origin, height range 57-76”, weight 102-320lb. CC range 31”-52”. Overall R was 95% (regardless of anthropomorphism). In pts with CC range 34”-46” (n=184/207 = 89%) DA was 96.8%. In pts with CC>46” DA was 91.8%. Conclusions: The PG showed excellent R regardless of anthropomorphism. The PG DA was 96.8% in almost 90% of a representative US cardiology outpatient clinic population, significantly exceeding the published conventional ECG R and DA.

physioglove_slide_presentation

physioglove ecg

ecg procedure

electrocardiogram ecg

ecg tracings

ecgunchanged ecg

regular cable ecg

physioglove heart rate

abnormal ecg heart rate

Documents

cakes recipes

daniel zanella and alexander weygers

minne hävisivät soneran rahat

iron mills essay

the last carnival i ever saw

chapter-01

1 시스템분석입문

rubik's cube solution

chapter 23

how computer monitors work

chapter 24

effective parenting: establishing boundaries

bhagavad gita

do you admire leonardo da vinci?

fortran

star wars original trilogy trivia (episodes iv-vi)

the dutch republic in international trade

xcdc14a

how computer keyboards work

tragic heroes