Rod Johnson: Spring Reference Documentation, http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/.
Gavin King: Hibernate Reference Documentation, http://docs.jboss.org/hibernate/stable/core/reference/en/html/.
Martin Fowler: The Dependency Injection Pattern, http://www.martinfowler.com/articles/injection.html.
Ben Collins-Sussman: Version Control with Subversion, http://svnbook.red-bean.com/.
Apache Project: Maven guides, http://maven.apache.org/guides/index.html.
Alex Garrett: JUnit Anti-Patterns, http://www.ibm.com/developerworks/opensource/library/os-junit/.