Genetic studies of male sterility in rape (Brassica napus L.). II. Analysis of esterase isoenzymes in an allo-nuclear male sterility system Liu, G.H.; Cai, M.; Sheng, X.Y.; Qin, X.Y. Oil Crops of China 16(4): 1-3 1994 https://eurekamag.com/research/002/626/002626404.php