1. G. A. Christie (1969 ), Proc. Symp. Cambridge , Syntex Pharmaceuticals, Maidenhead, p.93 .
2. E. B. Connell (1966 ), Advances in Planned Parenthood Vol. II Proceedings , A.A.P.P. Annual Meeting, Denver, Colo., Excerpta Medica, I.C.S. 138, p.74 .
3. Contraceptive Action of Continuous Low Doses of Norgestrel