I. P. Bangov,Comm. Dep. Chem. 1984,77, 459 (in Bulgarian).
I. P. Bangov,Org. Magn. Res. 1981,16, 296.
T. Tokuhiro, G. Fraenkel,J. Am. Chem. Soc. 1969,91, 5005.
I. P. Bangov,MATCH 1983,14, 235; I. P. Bangov, K. Kanev,J. Math. Chem. 1987, in press.
J. Gasteiger, M. Marsili,Tetrahedron 1980,36, 3219.
H. Eggert, C. Djerassi,J. Am. Chem. Soc. 1973,95, 3710.