Plasma concentrations of 15-ketodihydro-PGF2α, progesterone, oestrone sulphate, oestradiol-17ß, and cortisol during late gestation, parturition, and the early post-partum, period in llamas and alpacas - Aba, M A; Sumar, J; Kindahl, H (Anim Reprod Sc, 1998)