Character Strengths and Virtues
by Christopher Peterson and Martin Seligman

This is the original, scholarly work that describes the creation of the VIA Classification and details the research, assessment, consequences, and background of each of the 24 character strengths.

Positive Psychology at the Movies
by Ryan M. Niemiec and Danny Wedding

This book contains the latest research and practice tips for the 24 character strengths and discusses how the medium of movies can be used to practice strengths-spotting and to understand and develop strengths of character. Nearly 1500 movies are reviewed for each of the 24 strengths as well as movies that portray resilience, mindfulness, positive relationships, achievement, engagement, meaning, and positive emotions.

Mindfulness and Character Strengths
by Ryan M. Niemiec

This book offers a primer on character strengths, a primer on mindfulness, and discusses the research and practice involved in integrating these two popular areas of positive psychology. The second half of the book documents an 8-week program called Mindfulness-Based Strengths Practice (MBSP) that practitioners can study and implement either personally or with clients.

Now, Discover Your Strengths 
by Marcus Buckingham and Donald O. Clifton

This book from the Gallup Organization does not does character strengths, rather it reviews the use of talents and skills, which can be considered other types of strengths in humans. It reviews the value of looking within and deploying what is best in oneself and the vast majority of the book’s insights can be directly applied to the work with character strengths.

Average to A+: Realising Strengths in Yourself and Others (Strengthening the World)
by Alex Linley

This trade book from a UK thought leader discusses the use of strengths and understanding them more clearly. It emphasizes how strengths-spotting can be used and how to mobilize strengths in different settings.

Authentic Happiness
by Martin Seligman

The first book to outline and discuss the VIA Classification, it emphasizes the various areas of positive psychology in general. The book has been translated into numerous languages.

Smart Strengths - Building Character, Resilience and Relationships in Youth
by John M.Yeager, Sherri Fisher, and David N. Shearon

This guide-book is for parents, teachers, and coaches interested in building character strengths and resilience in youth.

Strengths Gym
by Carmel Proctor and Jenny Fox Eades

This practical book for teachers/parents focuses on various exercises for working with each of the 24 character strengths in children. It comes with a CD of worksheets and exercises.