Koester, Sola
Max Hueber Verlag, 1979
Buku Referensi
Bondarko, Aleksandr Vladimirovich
Nauk, 1971
Buku Referensi
Myuller, V.K.
Sovetskaja-Entsiklopedija, 1969
Buku Referensi
Mironova, S.A.
Gosudarstvennoe izdatel'stvo inostrannyx i natsional'nyx slovarej, 1958
Buku Referensi
Vyatyutnev, Mark Nikolayevich
Pedagogika, 1973
Buku Referensi