Maybe you're already familiar with the Interlibrary Loan system, which allows any public library patron to request a book; your local librarian will then track it down somewhere in the country and have it mailed to your local library so that you can borrow it. One time - no renewals. I've only used this method one or twice for hard to find books when I didn't want to (or couldn't afford to) buy them. I remember though that the book through the Loan System took a few weeks to arrive... from Wyoming! And was exactly what I needed.
My usual number of books at check-out - public domain image
But I've discovered another way: the Texshare card is a three-week-long library card that lets you walk up to the check-out desk of member libraries and Check-Out! Books. A limited number. Today I did not actually end up checking out the book I was interested in - because I could take fast enough notes - but my spiffy crisp-new little Texshare card gave me the confidence to walz into SMU's Fondren library and demand to know where, just exactly Where! my book might be. (I needed the help, it's a maze of a library spread over several buildings.)
Research. Easier than you think.