Waldmann, Herbert Abt. IV: Chemische Biologie, Max Planck Institute of Molecular Physiology, Max Planck Society;
Kirschbaum, S., & Waldmann, H. (1998). Three-step access to the tricyclic benzo[a]quinolizine ring system. JOURNAL OF ORGANIC CHEMISTRY, 63(15), 4936-4946. doi:10.1021/jo972035w.