London Socialist Commentary Publications 1953,
Buku Teks
Moscow: Novosti Press, 1977,
Buku Referensi
Zvorykin, A.A., author
UNESCO, 1977
Buku Teks
Ree, Jonathan, author
Clarendon Press, 1984
Buku Teks
Meade, James E., author
Macmillan, 1949
Buku Teks