Book review: Key to Parasites of Freshwater Fish of the U.S.S.R. by I.E. Bykhovskaya-Pavlovskaya, A.V. Gusev, M.N. Dubinina, N.A. Izyumova, T.S. Smirnova, I.L. Sokolovskaya, G.A. Shtein, S.S. Shul'man, V.M. Epshtein, L.F. Nagibina, E.V. Raikova, Yu. A. Strelkov, B.E. Bykhovskii, E.N. Pavlovskii - Hoffman, G. (Journal of Parasitology, 1966)