A mental health nurse and a psychiatric nurse are one in the same. If you work in the mental health/pscyh area, you will see a whole variety of things. Just getting your nursing degree is what is required. You do not have to have specific psychology degree.
Hi! I too am getting ready to take the PMHN certification test. The American Psychiatric Nursing Association website has this book listed on their website. I ordered it off of Amazon. Hope this helps and good luck! :) Psychiatric-Mental Health Nursing: Scope and Standards of Practice, 2nd Edition