Ráž, K: Biochemistry of drugs. XVII.Substances with antineoplastic effect. XXXVIII. Comparison of absorption, tissue distribution and excretion of radioactivity after application of 35S-labelled [delta]-(6-purinylthio)valeric acid, its ethoxycarbonylmethylamid and analogous N-substituted di- and triglycine ethylester derivatives in mice with Crocker´s sarcoma 180