Brian Beakley; Peter Ludlow
MIT Press , 2006
Buku Teks
Hawley, Georgina, author
Social Science Press, 1997
Buku Teks
Lipschutz, Martin M., author
Mc Graw Hill, 1969
Buku Teks
Edited by Richard Jolly... [at al]
Penguin Education, 1973
Buku Teks
Artikel Jurnal