H. W. Donias, G. D’Ancona, R. U. Pande, D. Schimpf, A. T. Kawaguchi, and H. L. Karamanoukian, “Heparin Dose, Transfusion Rates, and Intraoperative Graft Patency in Minimally Invasive Direct Coronary Artery Bypass”, HSF, vol. 6, no. 3, pp. 176-180, Feb. 2005.