Eucken Walter
William Hoodge and Co, 1950
Buku Teks
Ayoub, Mahmoud M., author
Mizan, 2003
Buku Teks
Piggin, Stuart
The University of Wollongong, 1984
Buku Teks
Ahmed, Akbar S., author
Routledge, 1988
Buku Teks
edited by Christian W. Troll.
Oxford University Press , 2003
Buku Teks