The following is a well-written tutorial: http://developer.java.sun.com/developer/onlineTraining/EJBIntro/EJBIntro.html
This book is great for starters:
Roman, E. Mastering Enterprise JavaBeans and the Java 2 Platform.
New York: John Wiley & Sons, 1999, ISBN: 0-471-33229-1.
Once you finished with the above two, go to:
" target="_blank" class="a2">http://java.sun.com/products/ejb/docs.html
and read EJB spec 1.0. Then read spec 1.1 and 2.0 when you have time.
Write some projects by you own. After
