7 books in series

Addison-Wesley Professional Ruby Series

Addison-Wesley Professional Ruby Series is a 7-book series with 7 released primary works first released in 2007 with contributions by Russ Olsen, Paul Dix, Michael Hartl, Obie Fernandez, Sandi Metz, and Bryan Liles.

Design Patterns in Ruby
Rails Way
Service-Oriented Design with Ruby and Rails
Ruby on Rails 3 Tutorial: Learn Rails by Example
Eloquent Ruby
The Rails 3 Way
Practical Object Oriented Design in Ruby