Font,J. et al.
Tetrahedron, 1978 , vol. 34, p. 791 - 798

Dneprovskii, A. S.; Mil'tsov, S. A.; Arbuzov, P. V.
Journal of Organic Chemistry USSR (English Translation), 1988 , vol. 24, # 10 p. 1826 - 1835
Zhurnal Organicheskoi Khimii, 1988 , vol. 24, # 10 p. 2026 - 2037

Korhonen, Ilpo O.O.; Korvola, Jorma N. J.
Acta Chemica Scandinavica, Series B: Organic Chemistry and Biochemistry, 1981 , vol. 35, # 6 p. 461 - 464