^ abcLutwak-Mann C, Adams CE (April 1957). "Carbonic anhydrase in the female reproductive tract. II. Endometrial carbonic anhydrase as indicator of luteoid potency: correlation with progestational proliferation". J. Endocrinol. 15 (1): 43–55. doi:10.1677/joe.0.0150043. PMID13439082.
^Rao, P. N., & Edwards, B. E. (1967). U.S. Patent No. 3,321,495. Washington, DC: U.S. Patent and Trademark Office.
^Gaunt R, Steinetz BG, Chart JJ (1968). "Pharmacologic alteration of steroid hormone functions". Clin. Pharmacol. Ther. 9 (5): 657–81. doi:10.1002/cpt196895657. PMID4175595. S2CID38695246. An interesting substance which has received little attention is the 3-cyclopentyl enol ether of progesterone (quingestrone). [...]
^Junkermann H, Runnebaum B, Lisboa BP (July 1977). "New progesterone metabolites in human myometrium". Steroids. 30 (1): 1–14. doi:10.1016/0039-128X(77)90131-3. PMID919010. S2CID28420255. In the Clauberg bioassay the 3β-hydroxy-4-pregnen-20-one shows about the same potency as progesterone (34). In regard to the biological activity of the 3α epimer no data are available.
^Junkmann, Karl (1954). "Gestagens of prolonged action". Naunyn-Schmiedebergs Archiv für Pharmakologie und Experimentelle Pathologie. 223: 244–53. ISSN0365-5423. Among a large no. of pregnane derivs. the esters of 17-α-hydroxyprogesterone (I), itself of weak lutein hormone action, have a strong and long-lasting gestagen action. The optimal results are obtained with I caproate. It permits the administration of depot doses in clear solns. Within the range of dosage used no androgenic effect was noted. It has no influence on growth and on the secondary sex characteristics in infantile and adult castrate male rats. The 3-enol esters of progesterone, which have a somewhat prolonged action, are less suited for depot administration because of their oxidizability.