Vernon R. Mattox, Richard B. Turner, Lewis L. Engel, Bernard F. McKenzie, Warren F. McGuckin, Edward C. Kendall,
Steroids derived from bile acids; 3,9-epoxy-delta 11-cholenic acid and closely related compounds. Journal of Biological Chemistry. ,vol. 164, pp. 569- 596 ,(1946) ,
10.1016/S0021-9258(17)41260-9