Field guide to algae and other “scums” in ponds, lakes, streams and rivers – by
Miriam Steinitz Kannan and Nicole Lenca Northern Kentucky University https://www.townofchapelhill.org/home/showdocument?id=28866
Phycokey – University of New Hampshire
http://cfb.unh.edu/phycokey/phycokey.htm
Varieties of Algae (with micrographs)
http://www.micrographia.com/specbiol/alg/alghome/alggen01.htm