http://www.webdesignerdepot.com/2009/04/how-to-make-a-photoshop-montage/
http://www.digitalartsonline.co.uk/tutorials/photoshop/digital-collage-techniques/#1
http://sir.kr/lecture/photoshopcs3/
Get Creative With Collage: Trends and Inspiration
https://www.smashingmagazine.com/2009/12/get-creative-with-collage-trends-and-inspiration/