"The practice of System and Network administration" by Tom Limoncelli and Christine Hogan[1] was, together with "Principles of Network and Systems Administration" by Mark Burgess have probably been the books that influenced my approach to sysadmin the most. I still have them. Between them they covered at a high level (at least back when I was sysadmin before devops and Kubernets etc) anything and everything from

- hardware, networks, monitoring, provisioning, server room locations in existing buildings, how to prepare server rooms

- and so on up to hiring and firing sysadmins, salary negotiations[2], vendor negotiations and the first book even had a whole chapter dedicated to "Being happy"

[1] There is a third author as well now, but those two were the ones that are on the cover of my book from 2005 and that I can remember

[2] Has mostly worked well after I more or less left sysadmin behind as well