1. V. A. Volkov, E. V. Vonskii, and G. I. Kuznetsova, Chemists [in Russian], Naukova Dumka, Kiev (1984). p. 218.
2. A. Cahouzs and S. Cloez, C.R.,38, 354 (1854).
3. O. Wallach, Ber.,32, 1872 (1899).
4. J. V. Braun Ber.,33, 1438 (1900).
5. R. H. McKee, Am. Chem. J.,36, 208 (1906).