"[E]vents from January 1848 through December 1855 [are] generally acknowledged as the 'Gold Rush' .... After 1855, California gold mining changed and is outside the 'rush' era." “The Gold Rush of California: A Bibliography of Periodical Articles”. California State University, Stanislaus (2002年). 2008年1月23日閲覧。
“The Northern California megaregion”. The Urbanist. San Francisco Planning and Urban Research Association (November/December 2007). November 21, 2009閲覧。
upstatecalifornia.com
“Upstate California”. Upstate California Economic Development Council. 2008年12月20日閲覧。