1. J. Mitchell, G. Dupuis andT. A. Geissman, Br. J. Derm.87, 235 (1972).
2. A. Lonkar, J. Mitchell andC. D. Calnan, Trans. St. John's Hosp. Derm. Soc.60, 43 (1974).
3. E. Rodríguez, Chemistry and Distribution of Sesquiterpene Lactones, Flavonoids inParthenium (Compositae): Systematic and and Ecological Implications. Unpublished Ph. D. Thesis, University of Texas, Austin (1975).
4. E. Rodríguez, H. Yoshioka andT. J. Mabry, Phytochemistry10, 1145 (1971).
5. W. Herz, inRecent Advances in Phytochemistry (Eds.T. J. Mabry, R. E. Alston andV. C. Runeckles; Appleton-Century Crofts, New York 1968), vol. 1, p. 229.