"State Symbols". Det Californiske Statsbibliotek. Arkiveret fra originalen 5. januar 2019. Hentet 2013-11-26.
census.gov
census.gov
Hyon B. Shin; Robert A. Kominski (april 2010). "Language Use in the United States: 2007"(PDF). United States Census Bureau. United States Department of Commerce. Hentet 27. maj 2013.