The phrase "pocket book" refers to a small book that can easily fit inside a pocket. It is usually used to describe a small notebook or diary that people carry around with them to write things down or keep important information. Full definition
We want to help you out by supplying your wallet or pocket book with more cash and when you need it. (nationalcashcredit.com)
I have bought several Bigger pockets books along with other financially beneficial books and this year I will be doing my first house hack. (biggerpockets.com)
Many different types of restaurants are around catering to all levels of pocket books. (globetrooper.com)