Weber, Eugen
D. C. Heath, 1959
Buku Teks
Naidis, Mark
Dryden Press, 1972
Buku Teks
Harthan, John
Thame and Hudson, 1981
Buku Referensi
Kelley, Donald R.
Harvard University Press, 1990
Buku Teks
Weber, Eugen
Boston: D.C.Heath and Company, (1959).
Buku Teks