1. V. V. Avidon, M. N. Shchukina, ZhOKh, 34, 2969, 1964.
2. F. Feigl, Spot Tests in Organic Analysis [Russian Translation], GKhI, 314, 1962.
3. H. Gilman, I. Beel, J. Am. Chem. Soc., 71, 2328?2331, 1949.
4. V. M. Zubarovskii, ZhOKh, 21, 2199, 1951.
5. A. Burawoy, A. Chandhuri, J. Chem. Soc., 648, 1956.