Ibrahim, Barbara (2008). Ibrahim, Barbara; Sherif, Dina H. (eds.). From Charity to Social Change: Trends in Arab Philanthropy (به انگلیسی). American Univ in Cairo Press. p. 5. ISBN9789774162077.
Abu-Nimer, Mohammed (2006). "Framework for Nonviolence and Peacebuilding in Islam". In Said, Abdul Aziz; Abu-Nimer, Mohammed; Sharify-Funk, Meena (eds.). Contemporary Islam: Dynamic, Not Static. Taylor & Francis. p. 145. ISBN978-0-415-77011-8.
brillonline.com
referenceworks.brillonline.com
Heck, Paul L. "Taxation". Encyclopaedia of the Qurʾān (به انگلیسی). Brill.