Encyclopedia of Modern Worldwide Extremists and Extremist Groups by 
Encyclopedia of Right-Wing Extremism in Modern American History by The following encyclopedias and reference databases will give you good scholarly overviews of your terrorist group and of broader movements such ecoterrorism and white supremacy.
They will also give you scholarly overviews on the cultural theories, rhetoric, ideologies, and thinkers that have influenced or inspired terrorist organizations, such as nationalism, globalization, the John Birch Society, and various conspiracy theories.
Check out the works cited at the end of relevant entries to find more information on your topic.
Culture Wars: An Encyclopedia of Issues, Viewpoints, and Voices
Encyclopedia of Modern Worldwide Extremists and Extremists Groups
Ref HN49 .R33 A85
Encyclopedia of Right-Wing Extremism in Modern American History
Ref HN90 .R3 A753
Extremist Groups: Information for Students
Ref HN90 .R3 E975
Encyclopedia of American Social Movements
Ref HN57 .E594
Encyclopedia of Nationalism: Fundamental Themes
Encyclopedia of Nationalism: Leaders. Movements, and Concepts
