Total assignment of 13C and 1H spectra of three isomeric triterpenoid derivatives by 2D NMR: an investigation of the potential utility of 1H chemical shifts in structural investigations of complex natural products - Reynolds,W.F.; McLean,S.; Poplawski,J.; Enriquez,R.G.; Escobar,L.I.; Leon,I. (Tetrahedron, 1986)