Two pyrrolo[1,2-a]azepine type alkaloids from Stemona collinsae Craib: structure elucidations, relationship to asparagamine A, and a new biogenetic concept of their formation - Seger,C.; Mereiter,K.; Kaltenegger,E.; Pacher,T.; Greger,H.; Hofer,O. (Chem Biodivers, 2004)