The Center for Certification Preparation and Review (www.ccprnet.org
) is a good place to start. They have study guides as well as a textbook list where a lot of the certification exam questions come from.
Also, if Professional Education Center (www.proedcenter.com
) has the certification prep course near, I would encourage your wife to attend. It was a GREAT informational course, and the instructor was very interesting. All 4 of us from my unit went to the class and passed the certification exam last September (we all have 5-25+ years experience)!
The credential is RNC-OB.
I wish your wife the best of luck. Let me know if either of you have any questions!