1. F. Brody and P. R. Ruby, in: Pyridine and Its Derivatives (E. Klingsberg, ed.), Interscience, New York (1960), Vol. 114, Pt. 1, p. 289.
2. N. S. Boodman, J. O. Hawthore, R. X. Msciantonio, and A. B. Simon, in: Pyridine and Its Derivatives (R. A. Abramovitch, ed.), Interscience, New York (1974), Vol. 14, Pt. 1, p. 245.
3. G. Jones, in: Comprehensive Heterocyclic Chemistry (A. R. Katritzky and C. W. Ress, eds.), PergamonPress, Oxford (1984), Vol. 2, p. 395.
4. E. P. Kohler, A. Graustein, and D. R. Merrill, J. Am. Chem. Soc.,44, 2536 (1922).
5. E. P. Kohler and Ch. F. H. Allen, J. Am. Chem. Soc.,46, 1522 (1924).