1. S. Gillespie, Org. Synth., 1934, 14, 81.
2. H. Oelschlaeger, A. Seeling, M. Radman, and H. Bockhard, Pharmazie, 2000, 55, 11, 825.
3. R. J. Lewis, C. A. Francis, R. E. Lehr, and C. Blank, Tetrahedron, 2000, 56, 5345.
4. O. V. Topuzyan, A. S. Nesunts, R. G. Paronikyan, L. K. Durgaryan, and A. Z. Akopyan, Khim.-farm. Zh., 1997, 31, No.1, 21 [Pharm. Chem. J., 1997, 31, No. 1, 19 (Engl. Transl.)].
5. K. Maekawa, H. Kajiwara, Y. Iseya, T. Igarashi, and T. Sakurai, Heterocycles, 2003, 60, 637.