1. Vorozhtsov, N.N., Osnovy sinteza promezhutochnykh produktov i krasitelei (Fundamentals of Synthesis of Intermediate Products and Dyes), Moscow: Goskhimizdat, 1955.
2. Venkataraman, K., Khimiya sinteticheskikh krasitelei (Chemistry of Synthetic Dyes), Leningrad: Goskhimizdat, 1956.
3. Efros, L.S. and Gorelik, M.V., Khimiya i tekhnologiya promezhutochnykh produktov (Chemistry and Technology of Intermediate Products), Leningrad: Khimiya, 1980.
4. Linhard, K. and Fridrich, A., FRG Patent 2614825, 1979.
5. Lülfing, A., FRG Patent 67018, 1981.