I can only assume this (copy-pasted from wikipedia)
The C Programming Language (sometimes termed K&R, after its authors’ initials) is a computer programming book written by Brian Kernighan and Dennis Ritchie, the latter of whom originally designed and implemented the C programming language, as well as co-designed the Unix operating system with which development of the language was closely intertwined
I can only assume this (copy-pasted from wikipedia)
I can confirm, K&R is the book written by Kernighan and Ritchie. It is/was the Bible of the C language.
Amazon link if you’re interested in the reviews.