Matikainen, Jorma; Kaltia, Seppo; Hase, Tapio; Kilpelaeinen, Ilkka; Drakenberg, Torbjoern; Annila, Arto Tetrahedron, 1993, vol. 49, # 36 p. 8007 - 8014 doi: 10.1016/S0040-4020(01)88024-8