by Thurman W. Arnold ... [et al.]
University of Pennsylvania Press, 1950
Buku Teks
Artikel Jurnal
Molander, Earl A.
McGraw-Hill, 1980
Buku Teks SO
edited by Daniel Bell and Irving Kristol
Basic Books, 1971
Buku Teks SO
Arnold, Thurman Wesley
Blue Ribbon Books, 1937
Buku Klasik