edited by Helmut Arntz
Press and Information Office of the Federal Government, 1961
Buku Teks
[, Springer], 2012
eBooks
Jones, Frank H., author
W. Heffer & Sons, 1972
Buku Teks
New York, N.Y. : New York University Press, 1977,
Buku Teks
Bromage, Mary C., author
McGraw-Hill, 1979
Buku Teks