If you would rather not to buy the required texts, there are free ways to access them. If WashU Libraries' copy is unavailable, you may be able to borrow one through Interlibrary Loan, or you may be able to borrow a copy through one of the local, public library systems:
AREA PUBLIC LIBRARIES
REQUIRED TEXTS
Bibliographic reference to the history of the United States and Canada from prehistory to the present.
Historical journal coverage of the world from 1450 to the present (excluding the United States and Canada).