Phenol oxidation and biosynthesis. Part XXII. The alkaloids of Erythrina lysistemon, E. abyssinica, E. poeppigiana, E. fusca, and E. lithosperma; the structure of erythratidine - Barton, D HR; Gunatilaka, A L; Letcher, R M; Lobo, A MF; Widdowson, D A (Chem Soc Perkin Trans I, 1973)