Lowi, Theodore J.
Basic books, 1971
Buku Teks
edited by James David Barber
Markham, 1970
Buku Teks
Clowers, Myles L., author
McGraw-Hill, 1973
Buku Teks
Yeric, Jerry L.
F.E. Peacock Publishers, 1983
Buku Teks
Brewster, Lawrence G., author
St. Martin`s Press, 1982
Buku Teks