Blackburn, Glenn, author
St. Martin's, 1985
Buku Teks
McWilliams, Wayne C., author
Adamantine Press, 1990
Buku Teks
Calvocoressi, Peter
Longman, 1992
Buku Teks
edited by John R. Burr
Greenwood Press, 1980
Buku Referensi
Calvocoressi, Peter
Longman, 1991
Buku Teks