Bergmann et al.
Journal of the American Chemical Society, 1957 , vol. 79, p. 4174,4177

Yudin, Andrei K.; Prakash, G. K. Surya; Deffieux, Denis; Bradley, Michael; Bau, Robert; Olah, George A.
Journal of the American Chemical Society, 1997 , vol. 119, # 7 p. 1572 - 1581

Dear,R.E.A. et al.
Tetrahedron, 1971 , vol. 27, p. 3345 - 3355