B. Wolff, Zentralblatt für Gynäkologie, 1904, No. 26.
Tridandani, Annali di Ostetrica, March, 1900.
R. Barnes, "The Induction of Labor," British Medical Journal, December 22, 1894.
See, e.g., Havelock Ellis, Man and Woman, fourth edition, pp. 344, et seq.