Ubuntu Certified Professional Study Guide
Ubuntu Linux secrets
Ubuntu Linux Bible
Linux Bible, 2008 Edition: Boot up to Ubuntu, Fedora, KNOPPIX, Debian, openSUSE, and 11 Other Distributions
Ubuntu for Non-Geeks: A Pain-Free, Project-Based, Get-Things-Done Guidebook
Ubuntu MATE User Guide
Ubuntu server essentials: unleash the true potential of Ubuntu server in your production environment using this administration guide
A Practical Guide to Ubuntu Linux
Ubuntu Linux Toolbox: 1000+ Commands for Ubuntu and Debian Power Users
Beginning Ubuntu Linux: [the complete introduction to Ubuntu ; fully revised and updated for 10.04]
Getting Started with Ubuntu 12.10
Linux Ubuntu 2010 часть 2 (Linux Ubuntu 8.10 для чайника)
A Practical Guide To Ubuntu Linux
Getting Started with Ubuntu 16.04
Ubuntu: Unleashed 2017 Edition
Beginning Ubuntu Linux: From Novice to Professional
Getting Started with Ubuntu 10.10
Ubuntu Linux toolbox : 1000+ commands for Ubuntu and Debian power users