Horrie, Chris
What is Islam?
Virgin Books, 1991
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Ahmed, Qadeeruddin
What is riba?
Justice (Retd.) Qadeeruddin Ahmed, 1994
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Sartre, Jean-Paul
What is literature?
Routledge classics, 2001
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Aronoff, Mark
What is morphology?
Blackwell, 2005
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Nemo, Philippe
What is the west?
Duquesne University Press, 2006
 Buku Teks SO