6,7-Dehydro Norgestrel;(17α)-13-Ethyl-17-hydroxy-18,19-dinorpregna-4,6-dien-20-yn-3-one;6,7-Dehydro Levonorgestrel;18,19-Dinorpregna-4,6-dien-20-yn-3-one, 13-ethyl-17-hydroxy-, (17α)- (9CI);Levonorgestrel Impurity 13(Levonorgestrel EP Impurity M);Levonorgestrel EP IMP M;Norgestrel 6(7)-Dehydro Impurity;Levonorgestrel EP impurity M