Isolation from Zanthoxylum and Artemisia spp: Araki, Miyashita, J. Pharm. Soc. Jpn. 48, 437 (1928); Sera, Shibuye, C.A. 24, 5742 (1930); Parihar, Dutt, Proc. Indian Acad. Sci. 25A, 153 (1947); King et al., J. Chem. Soc. 1954, 1392; Singh et al., J. Sci. Ind. Res. 15B, 190 (1956); Ban′kovskaya, Ban'kovskaya, C.A. 55, 17776c (1961). Structure and synthesis: Singh et al., Chem. Ind. (London) 1954, 1294. Improved synthesis: R. S. Mali et al., Indian J. Chem. 21B, 759 (1982).