Pyranocoumarins from tropical species of the genus Calophyllum: a chemotaxonomic study of extracts in the National Cancer Institute collection - McKee,T.C.; Covington,C.D.; Fuller,R.W.; Bokesch,H.R.; Young,S.; Cardellina II,J.H.; Kadushin,M.R.; Soejarto,D.D.; Stevens,P.F.; Cragg,G.M.; Boyd,M.R. (Journal of Natural Products, 1998)