Bob's nickname was “Elvis,” a 'reference to' the way he styled his hair. [=people called Bob “Elvis” because he styled his hair in the same way Elvis Presley did]
The course covers ancient history 'with' special 'reference to' the Roman Empire. [=the course is about ancient history and especially about the Roman Empire]
I have something further to add 'with reference to' [='with respect to', 'in regard to'] what was said earlier.
(..) - No, no, no. Get lost... - But it's my turn now. I've been waiting for hours. My turn... Hello. I'm coming to have a paper signed. Please take a seat. Do you have references? References? I do. So? We're all ears. "Kool & the Gang", "Earth, Wind & Fire". Those are good references, aren't they? (..)2011 The Intouchables
(..) - Yeah, it's fine. - Good luck. - Whatever. Now what? Now you let me handle it. THE INTOUCHABLES Do you have references? Well yes. I validated my CAFAD. A certificate of aptitude to take care of disabled persons. I validated it in a renowned institute in the Landes country in I have a high school (..)2011 The Intouchables