Sumner, William Graham
New Haven Yale University Press, 1950
Buku Teks
Hunt, Elgin F., author
MacMillan, 1987
Buku Teks
Hunt, Elgin F., author
Macmillan, 1962
Buku Teks
Hunt, Elgin F., author
Macmillan, 1984
Buku Teks
Hunt, Elgin F., author
Macmillan, 1961
Buku Teks