Rothstein, Andrew
Penguin Books , 1950
Buku Teks SO
Mongait, Alexander
Foreign Languages Publishing House, 1959
Buku Teks
Munich : Institute for the Study of the USSR
Majalah, Jurnal, Buletin
Schubert, Glendon A., Jr
University of Minnesota Press, 1956
Buku Teks
by E. Zaleski ... [and others]
Organisation for Economic Cooperation and Development, 1969
Buku Teks SO