The Stanford Auxiliary Libraries (SAL1&2, SAL3, and SAL Newark) house less-frequently-used monographs and journals. SAL1&2 are on campus and you can visit them; the others are at off-campus locations. Items from all the auxiliary libraries can be sent ("paged") to any library on campus.
How to page for delivery
Every item's SearchWorks record shows its location in the At the library section. Items in the Auxiliary Libraries will have a Request link next to the location name. Click this link and fill out the form; be sure to specify the library where you want the item delivered. Deliveries are made Monday through Friday, typically one or two business days after the request.