Gagey, Edmond M., author
Columbia University Press, 1948
Buku Teks
Downer, Alan, author
University of Minnesota Press, 1961
Buku Teks
Seduro, Vladimir
Research Program On The U.S.S.R, 1955
Buku Teks
Fergusson, Francis
Buku Teks
McKenna, George, author
McGraw-Hill, 1998
Buku Teks