To find books, you can search the library catalog (a box to do this is below, along with some instructions). Here are a few books - electronic and print - that I found that could get you started, but as you narrow down your topic you can use more specific search terms (specific sports, specific athletes, etc.) to find ones that are even more relevant to your research. The below are "secondary sources" - books that are not first-hand accounts of the topic. Depending on your research area, you might be able to use books as primary sources as well, especially if you are writing about someone who may have published an autobiography or memoir (just search for that person as the author).