edited by D.C. Hague
St. Martin's Press, 1962
Buku Teks
edited by Howard S. Ellis and Henry C. Wallich
Macmillan, 1963
Buku Teks
edited by B. R. Williams
John Wiley & Sons, 1973
Buku Referensi
Perlman, Mark, author
Macmillan, 1974
Buku Teks
edited by W.W. Rostow
St. Martin's , 1963
Buku Teks