blog source

http://www.adam-bien.com/roller/abien/entry/jpa_ejb3_killed_the_dao
http://www.oodesign.com/
http://gsraj.tripod.com/
http://www.allapplabs.com/java_design_patterns/factory_pattern.htm
http://www.codeproject.com/KB/architecture/#Design%20Patterns
http://xeon2k.wordpress.com/
http://snehaprashant.blogspot.com/2009/01/prototype-pattern-in-java.html