1. Premature parturition after infusion of corticotrophin or cortisol into fetal lambs;Liggins G.;J. Endocrinol.,1968
2. Premature delivery of foetal lambs infused with glucocorticoids;Liggins G.;J. Endocrinol.,1968
3. Sequential changes in plasma progesterone in the cow during the estrus cycle, pregnancy, at parturition and postpartum;Robertson H.;Can. J. Anim. Sci.,1972
4. WildenS DayM.(1991)Placental progesterone production in mid‐ to late‐gestation in the beef cow. Beef Cattle Research Report Ohio Agricultural Research and Development Center No. 91–92 pp.73–83.