1. E. Schmitz, Adv. Heterocycl. Chem., 1979, 24, 63.
2. E. Schmitz, Comprehensive Heterocyclic Chemistry, Ed. W. Lwowski, Pergamon Press, 1984, 1, 195.
3. H. W. Heine, in Small Ring Heterocycles, Part 2, Ed. A. Hassner, Wiley-Interscience, 1983, Ch. IV, 547–629.
4. A. V. Shevtsov, V. Yu. Petukhova, Yu. A. Strelenko, K. A. Lyssenko, I. V. Fedyanin, N. N. Makhova, Mendeleev Commun., 2003, 221.
5. A. V. Shevtsov, V. Yu. Petukhova, Yu. A. Strelenko, K. A. Lyssenko, N. N. Makhova, V. A. Tartakovskii, Izv. Akad. Nauk, Ser. Khim., 2005, 997 [Russ. Chem. Bull., Int. Ed., 2005, 54, 1021].