Sources

Bibliography: 

Pennak, Robert W. Fresh-Water Invertebrates of the United States. 3rd. ed. John Wiley and Sons, Inc., Print. 1953.

McFarland, Kenneth [Internet] Botany 111 Fall 2013. http://botany1112013.blogspot.com/

Patterson, D.J. Free-Living Freshwater Protozoa. Print. 1992.

G. W. Prescott Ph.D. The Freshwater Algae. Copyright 1954.