Constituent of coal tar, q.v. Isoln: Cook et al., J. Chem. Soc. 1933, 396. Synthesis: Cook, Hewett, ibid. 398; Clar, Ber. 76, 609 (1943); Buchta, Krger, Ann. 705, 190 (1967). NMR spectra: Cobb, Memory, J. Chem. Phys. 47, 2020 (1967). Review: Clar, Polycyclic Hydrocarbons Vol. 2, (Academic Press, New York, 1964) p 127. Review of toxicology and human exposure: Toxicological Profile for Polycyclic Aromatic Hydrocarbons (PB95-264370, 1995) 487 pp.