1. G. Grimmer (Ed.): Environmental Carcinogens: Polycyclic Aromatic Hydrocarbons, CRC Press, Boca Raton, Florida, 1983.
2. C. Boedeker, Liebigs Ann. Chem. 52, 100 (1844).
3. J. Dumas, Liebigs Ann. Chem. 5, 5 (1833).
4. M. Blumer, Chem. Geology 16, 245 (1975).
5. S.A. Wise, Org. Geochem., in print, and personal communication, 1985.