The Development of Ijtihad and Islamic Reform, 1750-1850 - An academic paper (by Knut S Vikør, University of Bergen) analyses the use of the concept by reforming thinkers in the 19th century. - http://www.smi.uib.no/paj/Vikor.html
Ijtihad :: Reinterpreting Islamic Principles for the Twenty-first Century - Report of a conference in 2004 sponsored by the United States Institute of Peace and the Center for the Study of Islam and Democracy entitled "Ijtihad: Reinterpreting Islamic Principles for the Twenty-first Century." - http://www.usip.org/pubs/specialreports/sr125.html
Ijtihad - An article from Wikipedia. - http://en.wikipedia.org/wiki/Ijtihad
The Principle of Ijtihad in Islam - An account of the concept from a Shia perspective. - http://www.al-islam.org/al-serat/ijtihad.htm