If we don't own the textbook you need, one of our partner libraries may, so you can request the physical book or a chapter/10% of it as a PDF.
Find it in our Primo library search like this example of a 9th edition of a textbook:
https://regent.primo.exlibrisgroup.com/permalink/01REGENT_INST/mdv8ae/cdi_elibro_books_ELB223627
Then sign in and either click the chapter titles to request one or the blue boxes that look like this:
For this book, Regent does own the 6th edition, which you can request using green links:
If a physical copy is mailed to you, you will need to mail it back.
If you get a PDF, it will be faster but there is a limit of how much (if the book is 550 pages, you can request up to 55)
You can try putting in both kinds of requests.
The 6th and 9th may be similar.
Publishers don't sell e-books of textbooks to libraries, so that is why there is no e-book of it.
You may be able to find other similar materials by the same author in Primo that are e-books.