MOBIUS is a consortium of academic libraries in Missouri. The COOL thing about MOBIUS is that you can transfer your search to the MOBIUS Catalog in one click from the WU Catalogs. MOBIUS requests are filled within 3-7 days. You'll be emailed once the item is available.
WorldCat identifies what items libraries worldwide (mainly US) hold. There are two interfaces WorldCat (FirstSearch) and WorldCat.org. Once you find your item, use the ILLiad link to request the item via Interlibrary Loan. You'll be emailed when the item is available