In addition to using books, you will also want to use articles from journals (magazines). To find them, you will need to search various databases. Below is a list of databases that will be helpful to your animal rights topic. Once you select the database you wish to use, enter your search terms. To find the article, you will need to take down the complete citation (title of magazine/journal, volume and issue number, date and pages). In many cases, you can click on View Now and the article will appear full text on your screen. We do not own access to all journals cited, however. If you need something the library does not own, you may obtain it free through Interlibrary Loan.
These databases serve as an index to articles in journals (magazines); some include newspapers, conference proceedings, etc. Because a single database can draw from hundreds or even thousands of sources, the more specific you can be in your search, the more successful the search will be. Again, instead of using "animal rights", use "horse slaughter", "factory farming", etc. Or you can add additional words to animal rights such as "animal rights" and history or "animal rights" and zoos. The quotation marks around 2 or more words tells the search engine that you only want those terms when they appear together.