.alpha.-Pyrrolidinone .alpha.-Pyrrolidone .gamma.-Aminobutyric lactam .gamma.-Aminobutyrolactam .gamma.-Butyrolactam 2-Oxopyrrolidine 2-Pyrol 2-Pyrrolidinone 2-Pyrrolidone 4-Aminobutyric acid lactam 616-45-5 Butanoic acid, 4-amino-, lactam Butyrolactam NSC4593 Pyrrolidon Pyrrolidone WLN: T5MVTJ