Hello Matt,
Probably the best photo reference book currently available on the Crusader is the Polish Photogallery title. It covers the Mk I, II, III and AA in various museums.
Other books include the Osprey title on Crusader, the now out of print Military Vehicle workshop booklet and Airfix title.
Overall there isn't a lot of material available in print.
If you are looking for a specific detail I might be able to help.
Regards