Zvegintsev, Vladimir Andreyevich, author
Ministerstva Prosveshheniya RSFSR, 1960
Buku Teks
Deyanova, Mariya, author
B`lgarskata Akademiya na Naukite, 1970
Buku Teks
Ivanova, Vera Fedorovna, author
Leningradskogo Universiteta, 1962
Buku Referensi
Berezyn, F.M., author
Vysshaya Shkola, 1979
Buku Referensi
Skobliova, Yelena Sergeyevna, author
Prosveshchenie , 1971
Buku Teks