
R. Fittig, Ann. 114, 54 (1860)
H. Gilman, Organic Chemistry I,
968, 975 (New York, 1943)
W. Huckel, Theoretical Principles of
Organic Chemistry, p405 (New York, 1955)
M. Stiles and R. P.
Mayer, J. Am. Chem;l. Soc. 81, 1497 (1959)
G. W. Wheland,
Advanced Organic Chemistry p 537 (New York, 1960)
C. J. Collins,
Quart. Rev. 14, 357 (1960)
L. F. Fieser and M. Fieser, Advanced
Organic Chemistry p 287 (New York, 1961)
D. Sands and D. G.
Bolteson, J. Org. Chem. 28, 2690 (1963)
R. T. Morrison and N.
Boyd, Organic Chemistry p 880 (Boston, 1966)