I also have a great fondness for Handbook of Neonatal Care
by Merenstein & Gardner.
When I was studying for my RNC exam I soaked up everything in Core Curriculum for Neonatal Intensive Care Nursing
by Deacon; and Manual of Neonatal Care
by Cloherty & Stark. I passed on my first attempt but expect I had also learned alot in the past from Comprehensive Neonatal Nursing
by Kenner, et. al. and Physical Assessment of the Newborn: A Comprehensive Guide to the Art of Physical Examination
by Tappero & Honeyfield.
For medication administration, I "cut my teeth" on Neofax
which is a great pocket-size drug book with the most pertinent information. I often would add my own personal notes to it. It's published each year. I absolutely love Neonatal Medications and Nutrition: A Comprehensive Guide, 3rd Ed.
by Zenk, et. al. I loved the 2nd edition and recently received the new 3rd edition.
Two of my new favorites are authored by Richard Polin and they are Fetal and Nneonatal Secrets
and Workbook in Practical Neonatology
. They are more geared to the neonatologist, but I found them incredibly insightful for my understanding of how and why things are done in the NICU setting.
By the way, the books by Zenk; Tappero & Honeyfield; and Merenstein & Gardner can all be purchased through NICU Ink publishers which is part of Neonatal Network at a bit of a discount. http://neonatalnetwork.com/nicuink/index.htm
If you want to start with just a couple of books, I'd suggest the Merenstein & Gardner and the Zenk books to start with, followed closely with Deacons book. The Neofax is never to be counted out if you want a good drug book to keep in your pocket.
Good luck in your endeavors!