O`Tuathail, Gearoid
Routledge, 1996
Buku Teks
Snow, Donald M., author
Pearson Longman, 2007
Buku Teks
edited by Ali Banuazizi, Myron Weiner
Indiana University Press, 1994
Buku Teks
edited by: John Halligan and Chris Paris
Longman Chesire, 1984
Buku Teks
Ibnu Hamad, author
Granit, 2004
Buku Teks