Staley, Eugene, author
Harper & Brother , 1954
Buku Teks
Schmitt, Bernard A.
Westview Press, 1979
Buku Teks
Schramm, Wilbur, author
Stanford Universuty Press, 1967
Buku Teks
Choudhury, Masudul Alam, 1948-, author
Ankara, 1993
Buku Teks
1994
Buku Teks