Clark, John M., author
National Bureau of Economic Resesarch, 1934
Buku Teks
Campion, H.
Oxford University Press, 1939
Buku Teks
Veblen, Thorstein, author
The Viking Press, Inc., 1954
Buku Teks
Arnold, Thurman Wesley, author
Blue Ribbon Books, 1937
Buku Klasik
Melman, Seymour, author
Simon and Schuster , 1974
Buku Teks