They can connect you with the places to start looking. They can help you find the materials you need. Using your key words, look in the library catalog. When you find a likely title, copy its call number, author and title. The librarian can help you locate the book.
Most books have lists of other resources too.
Ask your librarian to help you use special indexes that list the topics in these magazines. Your library will also have copies of the magazines. Ask specific questions that you couldn't answer in your library research. Don't ask the zoo to do your research for you.