If it is an electronic copy, you don't need to return it at all. That copy is yours to keep!
If it is a physical item, simply bring it back to the Library and drop it in one of our book drops near the entrance. One is located inside across from the Circulation Desk, and the other is outside the front door. If you return it over a campus closure, you may accrue fines because the item cannot be checked in or returned until operations resume.
ILL items cannot be kept past the end of the semester in which they are borrowed. Exceptions may be made on a case-by-case basis for graduate students, doctoral candidates, and faculty members working on research projects that extend past the traditional semester.
