Blue Team Field Manual, don't leave your network alone without giving this to your BOFH lazy lacky number 2 in command.
When you are being attacked, want to guard from an attack, or bed reminders of where that one log file you need for post mortem forensic mining is... The BTFM is the cheat sheet you want on your desk. I use it all the time.
Seriously though, Cybersecurity command line and GUI primary tools for Windows, Unix, Linux. All with explanations and basic to deep examples of use.