1. ARMSTRONG, C. N. (1953), Proc. Roy. Soc. Med., 46, 301.
2. Surg;BARR, M.L.;Gynec. Obstet,1954
3. L. (1955c) (cited Wilkins et L. (1956a), Lancet, i, 47.
4. BARR, M. L., and HOBBS, G. E. (1954), Lancet, i, IIo9.
5. Meeting;BRIGGS, D.K.; KUPPERMANN, H.S.,1955