· L. Witte et al., Planta Med., 53, 192, 1987(ms)
· JW. Loder et al., Aust. J. Chem., 22, 1271, 1969
· T. Sato et al., Yakugaku Zasshi, 100, 216, 1980(ir,nmr,ms)
· H. Fr. Grutzmacher et al., Chem. Ber., 111, 1962, 1978
· L. Witte et al., Planta Med., 5, 390, 1986
· P. Hanish et al., J. Chem. Soc. Perkin Trans. 2, 1202, 1977(cmr)
· EG. Sharova et al., Chem. Nat. Comp., 1, 117, 1977
· GS. Chappel et al., J. Pharm. Sci., 62, 414, 1973(pmr)