Peter (University of Leeds, UK) Lock 
The Routledge Companion to the Crusades [PDF ebook] 

A compilation of facts, figures, maps, family trees, summaries of the major crusades and their historiography, the Routledge Companion to the Crusades spans a broad chronological range from the eleventh to the eighteenth century, and gives a chronological framework and context for modern research on the crusading movement.

Not just a history of the Crusades, but an overview of the logistical, economic, social and biographical history, this is a core text for students of history and religious studies.