This site has the defintion, illustrations, and an audio explanation of the term.

For a concise summary of human blood types, this is a great resource. Discussion includes the topics of genotype, phenotype and agglutinins. There is also a nice pictorial table that summarizes the three blood types.

This site from the University of Illinois at Chicago provides an in-depth article on Human Genetics, with a focus on primarily population genetics. The article is factual and informative full of charts, formulas, and extensive text. A...