Cepa MM, Tavares da Silva EJ, Correia-da-Silva G, Roleira FM, Teixeira NA. Synthesis and biochemical studies of 17-substituted androst-3-enes and 3,4-epoxyandrostanes as aromatase inhibitors. Steroids. 2008 Dec 22;73(14):1409–15. doi: 10.1016/j.steroids.2008.07.001. PMID: 18691607.