AP Biology Links
Genetic Mapping and Linkage: Links to help understand genetic mapping and linkage during crossover
http://www.biologyreference.com/La-Ma/Linkage-and-Gene-Mapping.html
Another explanation page
http://www.ornl.gov/sci/techresources/Human_Genome/publicat/primer/prim2.html
Tutorial/Lecture on Linkage and Chromosome Mapping in Eukaryotes
http://www.scribd.com/doc/15041249/Gene-Lecture-8-Linkage
Search page for various open biology texts. Enter terms at the top and tons of info comes up for reference. Obtained through merlot.org (sign up for it as a teacher)
http://www.ncbi.nlm.nih.gov/sites/entrez
Linkage map explanation
http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=iga&part=A899