Need a book that has LIBRA as the location?
That's the library storage facility. You can read this guide about requesting items from LIBRA.
Need a book that's not in Penn Libraries?
You can use WorldCat or database information to request from other schools, through BorrowDirect, EZBorrow, or Inter-Library Loan (ILL).
Need a book that's at Penn but designated as rare?
Request to view it through your Research Account for Special Collections.
If you would like to suggest a title be added to the Penn Libraries collection:
You can fill out the online Purchase Request form.