Unix: A History and a Memoir, by Brian Kernighan
Looking forward to reading this! Had the pleasure of seeing Brian Kernighan and Ken Thompson speak at VCF East earlier this year, totally worth a watch: https://www.youtube.com/watch?v=EY6q5dv_B-oI highly recommend hitting up a Vintage Computer Festival if you've got the opportunity (http://vcfed.org/wp/festivals/). Not only did Kernighan and Thompson speak, but also Joe Decuir of Atari & Amiga fame.