1. Antisera reactive directly to estrone sulfate
2. R. I. Cox, Y. S. Pan, M. S. F. Wong, and R. M. Hoskinson (1981 ) - Proc. Aust. Soc. Reprod. Biol., Christchurch. Abstr. No. 98.
3. A. P. F. Flint, R. D. Burton, J. E. Gadsby, P. T. K. Saunders, and R. B. Heap (1979 ) - Maternal Recognition of Pregnancy (Ciba Fdn Symp. No. 64, New Series), pp209 -228 . Excerpta Medica, Amsterdam.