Many of these publications can be found on-line at - https://archive.org The Internet Archive
Programming the PET/CBM - Raeto Colin West - COMPUTE! books
Many would refer to this book as the PET programming bible, as it is a very lengthy and complete overview of the PET computers. With plenty of information on basic commands (as well as additional commands) , programming with peripherals and the differences in the various PET/CBM models.
PET/CBM Personal Computer Guide - Adam Osborne and Others - Osborne McGraw Hill
Not as expansive as Programming the PET/CBM this books is still a great reference. Aspects of using peripherals, programming, hardware features and memory maps. The Personal Computer Guide has gone through several printings and co-authors, ending with the third edition.
Complete Commodore Innerspace Anthology - Karl Hildon -Transactor Publications
Not specific on just the PET the Anthology covers most of the Commodore 8-bit line with reference tables, charts, memory maps, pinouts, etc. A must-have for the Commodore tinkerer who has multiple Commodore 8-bit computers. [on-line scanned book!] or buy the original (easier to manage) from the author Karl Hildon
Machine Language for the Commodore 64/128 and other Commodore Computers - Jim Butterfield - Brady Books
Jim Butterfield has been a 6502 user even before the PET was released. He has over the years helped many a Commodore neophyte get a grip on programming in machine language. The native language of the 6502 microprocessor of the PET and many other Commodore 8-bits. His book goes over all the Machine Language commands and gets us started in low-level programming. Very useful if you want to get the most out of your PET programming efforts. [You can find the book on-line here] and the companion disk (which includes Unicopy) [here]
6502 Assembly Language Programming and 6502 Assembly Language Subroutines - Lance Leventhall - Osborne McGraw Hill
Not specifically geared for the PET these two books cover programming the 6502 microprocessor quite well the first goes over the processor commands and operations and the second provides plenty of useful (machine non-specific) 6502 subroutines that you can use in your own projects.
the PET Revealed - Nick Hampshire - Nick Hampshire Publishing
Where the Programming the PET/CBM was the bible for programming the PET - PET Revealed covers a lot of the technical hardware and interfacing aspects of the PET including on using some of the lesser known features of the 6520 interface chip.
Hands On BASIC with a PET - Herbert Peckham - McGraw Hill
This is the book I learned BASIC from while in high school - it covers most of the language and a little on the keyboard graphics. Good for beginners.
PET Fun and Games - Glen Fisher - Osborne/McGraw Hill
Selected programs from the popular PET tape magazine Cursor. (many of which are on-line in my PET Games Archive) Very well done PET specific type-in game programs.
Some more classic computing books are available at https://atariarchives.org, who have been doing a bang-up job of preserving classic computing resources for the internet.
MicroSoft BASIC (the version used in the PET) was very popular in the 70s and 80s and ran on many computers during that time. Thus a lot of books have been written about programming in BASIC. Here is a list of some BASIC learning books as well as books with BASIC examples that would work (sometimes with a little modification) on the PET. A great way to learn BASIC syntax and get ideas on how to accomplish your programming challenges.
BASIC 2nd Edition - Albrecht, Finkel, Brown - Wiley
One of the earlier BASIC tutorials does an excellent job of covering all the most used commands with sample lessons.
BASIC Computer Games - Microcomputer Edition - David Ahl
More BASIC Computer Games - David Ahl
Big BASIC Games - David Ahl
BASIC Computer Adventures - David Ahl
The BASIC Computer Games and More BASIC Computer Games are probably the best know of the BASIC games books, containing many Games and wonderments written in BASIC for you to type-in play and experiment with. Many of the programs in the later books were reprinted from the popular home computing magazine “Creative Computing”. A must for BASIC fans. Many on-line at atariarchives.org!
Giant Book of Computer Games
Second Giant Book of Computer Games
Golden Flutes and Great Escapes - Writing Adventure Games
(Several other books) - Tim Hartnell
Tim Hartnell has written so many wonderful BASIC games books all of which are interesting. A wide variety of programs can be found even a version of chess (2nd Giant Book of Computer Games) all written in BASIC.
Many of these magazines started in the mid to late 70s and covered PET related topics till about 1983 when the Commodore 64 eclipsed the PET market.