I’ve found that if I PDF compress these scans they take up way less space (from 100s to few MBs) and Preview is much snappier when browsing/searching through them.
The compressor for PDF files online: https://www.sejda.com/compress-pdf
In the day and age of the internet you can find a lot of books online. Here’s a few tips on how to find them.
Google is the best search engine for the web. Use it to find what you are looking for.
Here are some tips on how to search Google efficiently.