Here are some sources that will be helpful:
1) The Crusades (Call # 909.07 A556e 2003) is the encyclopedia that contains some primary sources.
2) Encyclopedia of the Crusades (Call # 909.07 A556e 2003 ) - there are some primary sources in this encyclopedia, as well.
Also, both of the encyclopedias have bibliography, and that will give one a good start to find additional sources and books about the research topic.
