USSR, [date of publication not identified]
Buku Teks
[publisher not identified], 1967
Buku Teks
Dallin, David J., author
Hollis & Carter, 1951
Buku Teks
Webb, Sidney, author
Longman, 1947
Buku Teks
Bauer, Raymond A., author
Harvard University Press, 1952; 1959
Buku Teks