1. Arch Pharm Ber Dtsch Pharm Ges. 1970 Feb;303(2):107-15. [Modification of active methylene compounds by the nitro-group during amino-methylation]. [Article in German]. Kreutzberger A, Abel D. PMID: 5267703 [PubMed - indexed for MEDLINE]. MeSH Terms. Amines; Chemistry, Pharmaceutical; Fluorenes*; Methane*; Methylation*; Piperidines; Pyridines; Triazines*. Substances. Amines; Fluorenes; Piperidines; Pyridines; Triazines; Methane.