Obviously, reading the book and taking notes is not helpful if you need the information fast, so start in the table of contents. Many tables of contents are extensive and you will easily find what you are looking for. Find the closest topic to your issue. Most non-fiction books also have an index. There, the words/topics are listed in alphabetical order. Once you find your topic, you may find it is divided into subtopics, so pick what is closest to your issue and go to that page in the book.