1. The origins of open heart surgery at the University of Minnesota 1951 to 1956 
Richard A. DeWall, MD 
The Journal of Thoracic and Cardiovascular Surgery 
Volume 142, Issue 2, Pages (August 2011)
DOI: /j.jtcvs
Copyright © 2011 The American Association for Thoracic Surgery Terms and Conditions

2. Figure 1 Helical reservoir pump oxygenator, 1955.
The Journal of Thoracic and Cardiovascular Surgery  , DOI: ( /j.jtcvs )
Copyright © 2011 The American Association for Thoracic Surgery Terms and Conditions