title: [Studies on long acting contraceptives: synthesis of 17 beta-steroid esters].
mesh_terms: D004952:Esters; D009640:Norethindrone / Q000138:chemical synthesis*; D009644:Norgestrel / Q000138:chemical synthesis*
chemical_list: D004952:Esters; D009644:Norgestrel; D009640:Norethindrone