Anthony H. Cordesman.Peace and War: The Arab–Israeli Military Balance Enters the 21st Century. Greenwood Publishing Group. 2002. p. 243: "Hamas is a radical Islamic fundamentalist organization that has stated that its highest priority is a Jihad (holy war) for the liberation of Palestine."
Meir Litvak. "Hamas: Palestinian Identity, Islam, and National Sovereignty," in Asher Susser (ed.) Challenges to the Cohesion of the Arabic State. Moshe Dayan Center for Middle Eastern and African Studies. Tel Aviv University. 2008. p. 153: 'One of the secrets behind the success of Hamas is that it is an Islamic and national movement at one and the same time,'