Piliostigmin, a 2-phenoxychromone, and C-methylflavonols from Piliostigma thonningii - Ibewike,J.C.; Ogundaini,A.O.; Ogungbamila,F.O.; Martin,M.-T.; Gallaard,J.-F.; Bohlin,L.; Païs,M. (Phytochemistry, 1996)