Klepp, R., Lønning, P. E. . and Kvinnsland, S. (1989) “Plasma Estrone and Estrone Sulphate in Breast Cancer Patients Treated with the Aromatase Inhibitor CGS 16949A”, Acta Oncologica, 29(4), pp. 469–471. doi: 10.3109/02841869009090031.