"Annelid." Microsoft. Encarta. Online Encyclopedia. 2001. 1997-2001 Microsoft Corporation.
    <encarta.msn.com>.

Annelid Resources. Ed. Geoff Read. 2000. Annelid Resources. 20 Apr. 2001
    <http://biodiversity.uno.edu/~worms/annelid.html>.

Biological Diversity: Animals I. Ed. M. J. Farabee. 2000. 1 May 2001
    <http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookDiversity_7.html>.

Biological Sciences Website. Annelida. 25 Apr. 2001
    <http://www?biol.paisley.ac.uk/courses/Tatner/biomedia/units/anne1.htm>.

Fact Monster. Annelida. The Columbia Electronic Encyclopedia. 23 Apr. 2001
    <http://www.factmonster.com/ce6/sci/A0804124.html>.

- -. Platyhelminthes. The Columbia Electronic Encyclopedia. 24 Apr. 2001
    <http://www.factmonster.com/ce6/sci/A0839338.html>.

Introduction to Annelida. Ed. University of California Museum of Paleontology. 20 Apr. 2001
    <http://www.ucmp.berkeley.edu/annelida/annelida.html>.

Introduction to Platyhelminthes. Ed. University of California Museum of Paleontology. 20 Apr. 2001
    <http://www.ucmp.berkeley.edu/platyhelminthes/platyhelminthes.html>.

Land Of Lakes Bait. About Leeches Website. 19 Apr. 2001
    <http://www.lolbait.com/aboutleeches.htm>.

Leeches. Ed. Mark Kazee and Lee Townsend. Dec. 1995. University of Kentucky Entomology. 19 Apr. 2001
    <http://www.uky.edu/Agriculture/Entomology/entfacts/misc/ef013.htm>.

Mandaville, S. M. Class Oligochaeta. 28 Apr. 2001
    <http://www.chebucto.ns.ca/Science/SWCS/ZOOBENTH/oligocha.html>.

Parasites and Parasitological Resources. Class Monogenea. 25 Apr. 2001
    <http://www.biosci.ohio?state.edu/~parasite/monogenea.html>.

Phylum Annelida. Ed. Lee Couch. 16 Aug. 1998. 3 May 2001
    <http://biology.unm.edu/biology/bio404/Annelida.html>.

Phylum Annelida. Ed. Philip Myers. 13 Feb. 1995. Animal Diversity Web. 24 Apr. 2001
    <http://animaldiversity.ummz.umich.edu/annelida.html>.

Phylum Annelida. Ed. Virtual Lab Book. Vers. 5th Edition. 1 May 2001
    <http://www.sidwell.edu/us/science/vlb5/Labs/Classification_Lab/Eukarya/Animalia/Annelida/>.

Phylum Platyhelminthes. Ed. Philip Myers. 13 Feb. 1995. 29 Apr. 2001
    <http://animaldiversity.ummz.umich.edu/platyhelminthes.html>.

Phylum Platyhelminthes. Ed. Virtual Lab Book. Vers. 5th Edition. 10 May 2001
    <http://www.sidwell.edu/us/science/vlb5/Labs/Classification_Lab/Eukarya/Animalia/Platyhelminthes/>.

Sauter, Steve. Planarians.org. 2 May 2001 <http://www.stevesauter.com/planarians/>.

Smith, Jim. Monogenia. The World Of Parasites. 25 Apr. 2001
    <http://martin.parasitology.mcgill.ca/jimspage/biol/monogen.htm>.

Towle, Albert. Modern Biology. Orlando: Hold, Rinhart and Winstun, 1993.

Van Egmond, Wim. Bristleworms and Their Larva. 20 Apr. 2001
    <http://micscape.simplenet.com/mag/artmar99/polych.html>.