There are a few different ways to refer students to the Libraries. For undergraduates working on assignments and basic questions about locating resources and services, you can refer to the PCL Desk or the Ask a Librarian email or IM service.
Keep in mind that there may be a Guide for the student's UGS or RHE course. Search by course title or professor's name in Guides.
For graduate students working on more complicated research projects (or undergraduates working on a multi-semester project) you can refer to the subject specialist for that subject area.