J2EE Development without EJB
by Rod Johnson and Juergen Hoeller

J2EE Development without EJB is the runaway best-seller that dares to say "You can build viable enterprise applications, using J2EE, without EJB.

Chapter 1: Why "J2EE Without EJB"?" of Expert One-on-One J2EE Development without EJB is available for a free download courtesy of Wily.

J2EE Design and Development
by Rod Johnson

In Expert One-on-One J2EE Design and Development, Rod Johnson defines the code and principles that founded the Spring framework. 

Chapter 1 "J2EE Architectiures" of Expert One-on-One J2EE Design and Development is available for a free download courtesy of TheServerSide.com.

Chapter 4 "Design Techniques and Coding Standards for J2EE Projects" of Expert One-on-One J2EE Design and Development is available for a free download courtesy of TheServerSide.com.

Pro Spring
by Rob Harrop

Pro Spring is a comprehensive resource on Spring, full of practical, real-world examples illustrating the latest features of the framework.

Professional Java Development with the Spring Framework
by Rod Johnson, Juergen Hoeller, Colin Sampaleanu, Alef Arendsen

The in-depth book on core Spring by the creators of the framework.

Chapter 1: Introducing the Spring Framework" of Professional Java Development with the Spring Framework is available for a free download courtesy of Wily.

Spring: A Developer's Notebook
by Bruce Tate, with contributions from Keith Donald

Spring: A Developer's Notebook is a hands-on, no nonsense guide to getting productive with Spring.

Expert Spring MVC and Web Flow
by Seth Ledd, with contributions from Steven Devijver and Colin Yates

Expert Spring MVC and Web Flow provides in-depth coverage of these two very popular and powerful web frameworks.

Spring: Framework für die Java-Entwicklung
by Eberhard Wolff

German book about the Spring Framework.

Beginning Spring Framework 2
by Thomas Van de Velde, Bruce Snyder, Christian Dupuis, Sing Li, Anne Horton, Naveen Balani

Beginning Spring Framework 2 shows beginning Java developers how to build serverside Java applications using the latest 2.0 release of the Spring Framework. The book does not assume any previous knowledge of J2EE--in fact, the authors argue that beginners learn more quickly by starting directly with Spring.

Chapter 1: Jump Start Spring 2 of Beginning Spring Framework 2 is available for a free download courtesy of Wily.

Building Spring 2 Enterprise Applications
by Interface21, Seth Ladd, Bram Smeets

Building Spring 2 Enterprise Applications covers the first steps of using Spring while discussing the relevant technologies that Spring can be integrated with, what to be aware of, and how working with Spring makes them easier to use.  It focuses on the most useful features of Spring, including persistence and transaction management as well as the complete Spring web tools portfolio.