Dennis,N. et al.
Tetrahedron Letters, 1976 , p. 2959 - 2960

Katritzky, Alan R.; Cutler, Alan T.; Dennis, Nicolas; Sabongi, Gebran J.; Rahimi-Rastgoo, Soheila; et al.
Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1980 , p. 1176 - 1184