Bash Pocket Reference: Help for Power Users and Sys Admins
Linux Command Line and Shell Scripting Bible
The Linux Command Line: A Complete Introduction
Linux Bible
Python Pocket Reference: Python In Your Pocket (Pocket Reference (O'Reilly))
How Linux Works: What Every Superuser Should Know
LINUX: Easy Linux For Beginners, Your Step-By-Step Guide To Learning The Linux Operating System And Command Line (Linux Series Book 1)
Ubuntu Unleashed 2017 Edition (Includes Content Update Program): Covering 16.10, 17.04, 17.10
Linux: The Fundamentals Of The Linux Operating System: A Complete Beginners Guide To Linux Mastery.