Schwartz, Benjamin
Harvard University Press, 1952, 1961
Buku Teks
Schwartz, Benjamin
Harper Torchbooks and The Academy Library, 1967
Buku Teks
War Departement, 1944
Buku Referensi
Singer, P. W.
Cornell University Press, 2003
Buku Teks
Nelson, Ralph L.
Russell Sage Foundation , 1967
Buku Teks