In many cases you will still use print content, but you may not want to read the entire book to find what you need. To save yourself time, use the index at the back of the book or the Table of Contents in the front to look up your topic. For example, if I were to use the Synopsis and Classification of Living Organisms to look up information on Balanus, I would use the index. The index tells me to flip to page 228 for the information.