About algae. (n.d.). Retrieved July 18, 2014, from Natural History Museum website

Algae. (2009). In K. L. Lerner & B. W. Lerner (Eds.), The Gale Encyclopedia of Science (4th ed.). Detroit: Gale.

Algae. (2010, May 5). Retrieved July 18, 2014, from United States Department of Agriculture website:  

Algae basics. (n.d.). Retrieved July 18, 2014, from All About Algae.com website:

Andersen, R. A., & Lewin, R. A. (2014). Algae. Retrieved from Encyclopaedia Britannica database.

Annelida: worms and leeches. (n.d.). Retrieved July 18, 2014, from CSIRO website:

Croft, M. T., Warren, M. J., & Smith, A. G. (2006, August). Algae need their vitamins. Retrieved from National Center for Biotechnology Information website:

Earthworm. (n.d.). Retrieved July 18, 2014, from Fairfax County Public Schools website:

Graham, L. E., Graham, J. M., & Wilcox, L. W. (2009). Chapter 23 terrestrial algal ecology. In Algae (2nd ed.).

Mckenzie, G. (n.d.). The Earthworm. Retrieved July 23, 2014

Pipe, A.E. and Cullimore, D.R. (1980) An implanted slide technique for examining the effects of herbicide Duiron on soil algae. Bulletin of Environmental Contamination and Toxicology 24, 306-312.

The Secret Life of Soil: The Soil Food Web. (n.d.). Retrieved from Knowledge Atlas website: