Terrorism has always been a part of history. To examine this more further we have browsed and collected from a number of websites the following books that focus on the history, culture, and reasons for terrorism.Beyond al-Qaeda: Part 1: The Global Jihadist Movement -- Book Bank
Beyond al-Qaeda: Part 2: The Outer Rings of the Terrorist Universe -- Book Bank
Encyclopedia of Terrorism by Harvey W. Kushner -- Avaxhome
The New Terrorism by Walter Laqueur -- Avaxhome
The Culture Of Terrorism by Noam Chomsky -- Avaxhome
Psychology Of Terrorism by Various Authors -- Avaxhome
In The Name Of Terrorism by Carol K. Winkler -- Englishtips (free registration required)
Terrorism Reference Library, 1st Edition (3 volumes) by Various Authors -- Avaxhome
Deadly Connections: States that Sponsor Terrorism by Daniel Byman -- Avaxhome
Battling Terrorism in the Horn of Africa by Robert I. Rotberg -- Gigapedia (free registration required)
The Four Faces of Nuclear Terrorism by Various Authors -- Avaxhome
The Media and the War on Terrorism by Stephen Hess -- Gigapedia (free registration required)
Bookyards has a number of documents, speeches, and books that pertain to terrorism here.
Bookyards has also made a list of free online libraries that have a focus on terrorism and security issues. That link is here.