I have a book handy but its size is beyond what yahoo allows me to upload. I might be able to send it directly to u if you want.

but a few hints: the best reference is sun  itself, but when it gets to wireless  programming you have to be clear as what exactly you want to do.
J2ME has a wide scope , you can not find one reference for all. there are different aspects into wireless programming  with j2me  / Java ME
such as:
1. Bluetooth programming
2. J2ME and Web service client programming (your mobile device is connected to web services)
3. Ad hoc networks / Sensor networks (all mobile devices communicate with each other)
4. J2ME devices connecting to fixed networks (JXME - JXTA micro edition) http://jxme.jxta.org
5. and many more

diagram in http://java.sun.com/javame/technologies/index.jsp shows you all the bits and pieces of J2ME over different configurations CDC and CLDC. some new JSRs are in progress and have been started recently.

I will send you my book and you can start  with that. it will give you a feeling as what exactly you want to do. that would make it lot easier for you to dig into Sun website for more references.