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.
(..) Can you get me access to this man here? Browning. Fischer Senior's right-hand man. Fischer Junior's godfather. It should be possible, if you can get the right references. References are something of a speciality for me, Mr. Saito. BROWNING: I'm not smelling settlement here. Take them down. LAWYER: (..)2010 Inception