1. Understanding investigative clinical trials
Robert W. Barnes, MD 
Journal of Vascular Surgery 
Volume 9, Issue 4, Pages (April 1989)
DOI: / (89)
Copyright © 1989 Society for Vascular Surgery and International Society for Cardiovascular Surgery, North American Chapter Terms and Conditions

2. Fig. 1
Recent trends in funding of clinical trials by the National Institutes of Health. (NCI, National Cancer Institute; NHLBI, National Heart, Lung and Blood Institute; NINCDS, National Institute of Neurological and Communicative Disorders and Stroke.)
Journal of Vascular Surgery 1989 9, DOI: ( / (89) )
Copyright © 1989 Society for Vascular Surgery and International Society for Cardiovascular Surgery, North American Chapter Terms and Conditions

3. Fig. 2
Trends in reporting types of clinical studies based on 749 abstracts accepted at the annual joint meetings of the Society for Vascular Surgery and the International Society for Cardiovascular Surgery for the periods 1972 to 1979 (1970s) and 1980 to 1988 (1980s). (CS, Cross-sectional; RET, retrospective; COH, cohort (prospective); UCT, uncontrolled clinical trial; NCT, nonrandomized controlled trial; RCT, randomized controlled trial; LAB, laboratory research.)
Journal of Vascular Surgery 1989 9, DOI: ( / (89) )
Copyright © 1989 Society for Vascular Surgery and International Society for Cardiovascular Surgery, North American Chapter Terms and Conditions