From Pongamia glabra Vent., Leguminosae: Beal, Katti, J. Am. Pharm. Assoc. 14, 1086 (1925); Rao, Rao, J. Indian Chem. Soc. 17, 526 (1940); Bhat et al., J. Am. Oil Chem. Soc. 33, 197 (1956). Structure: Limaye, Rasayanam 1, 1 (1936), C.A. 31, 22069 (1937); Manjunath et al., Ber. 72B, 39 (1939). Synthesis: Seshadri, Venkateswarlu, Proc. Indian Acad. Sci. 13A, 404 (1941); 17A, 16 (1943); Kawase et al., Bull. Chem. Soc. Jpn. 28, 273 (1955); Rao, Seshadri, Proc. Indian Acad. Sci. 33A, 168 (1951); Aneja et al., Tetrahedron 2, 203 (1958); Raizada et al., J. Sci. Ind. Res. 19B, 76 (1960).