I ordered some books from Amazon that I just love - I love all of them!
Most of them are about Art Journaling, but one is about Collage.
I would warmly recommend all of them. The Collage workbook by Randel Plowman, Journal It! by Jenny Doh, Creative wildfire by L.K. Ludwig, The Art Journal Workshop by Traci Bunkers and Journal Spilling by Diana Trout. Get any one of them -There is goodness inside. YUM!!
I've read only two of them yet, butI just want to go on reading the others RIGHT NOW. But I guess I should get my hands on some paint and play in my journal for an hour or two, and them get back to the reading.