Imperial Valley newspapers at the Library of Congress. Format is digital scan.The Library of Congress' Chronicling America site makes digital scans of historical newspapers freely available online. This link is to the 69 newspapers for the state of California. The list included The Imperial Valley Press in its various iterations:
Imperial Press and Farmer 1901-1903
Imperial Press 1901-1901
The Imperial Press 1903-1906
Imperial Valley Press and The Imperial Press 1906-1907
Imperial Valley Press 1907-[1945]