1. V. P. Litvinov and V. D. Dyachenko, Usp. Khim. 66, 1025 (1997).
2. D. R. Garud, M. Koketsu, and H. Ishihara, Molecules, 12, 504 (2007).
3. J. Młochowski and M. Giurg, in: R. R. Gupta (editor), Topics in Heterocyclic Chemistry, Springer-Verlag, Berlin, Heidelberg (2009), Vol. 19, p. 287.
4. J. Młochowski, K. Kloc, R. Lisiak, P. Potaczek, and H. Wójtowicz, ARKIVOC, vi, 14 (2007), and the literature cited therein.
5. H. Heimgartner, Y. Zhou, P. K. Atanassov, and G. L. Sommen, Phosphorus, Sulfur Silicon Relat. Elem., 183, 840 (2008).