Holcombe, Arthur N.
Harvard University Press, 1940
Buku Teks
Mills, C. Wright, author
Oxford University Press, 1951
Buku Teks
Mackenzie, Gavin.
Cambridge University Pres, 1973
Buku Teks
Campbell, John C., author
Frederick A. Preger, 1960
Buku Teks
Deegan, Heather, author
Routledge, 1996
Buku Teks