The eBook and Database resources below will provide you with a great variety of resources from reliable sources. Also, each eBook or database article that you use provides you with the citation information that you need. Simply look for the CITE button on the information page
As with many subjects, there are many quality resources about selective breeding for the animal that you selected on the internet, or free web. I would suggest searching "Selective Breeding" followed by the name of the animal that you are researching, for example, "Selective Breeding - Dogs" or "Selective Breeding - Cattle."
As with any free web search, or Google search, you will receive thousands, if not millions of "hits." Remember that much of the information on the free web is questionable because we don't know where it comes from. Remember what we learned in sixth grade when you are evaluating websites and determining if you should use a site or not. The C.A.R.S. acronym should help you decide.
You can easily enter a website into Noodletools to help create a citation. Make sure to fill as many blanks as possible, but if you simply can find the information it asks for, leave it blank.