Referring to professors in papers

[broean01]

This is sort of off-topic, but I couldn't find a better forum to ask in.

I'm writing a paper for my internship, and I need to refer to one of my professors for purposes of background information. I want to do this in a professional manner.

Should I say Professor Xxxx Xxxxxxx, Ph.D.?
Doctor Xxxx Xxxxxxx?

 

[broean01]

I just noticed that I accidentally clicked on the math forum instead of the physics one. Feel free to move this.