Use OneSearch. Books may only have broad subject headings, so if you are seeking information on a more specific topic you may have to broaden your search. For instance you might not find anything under the name of an individual who might be covered in a collective biography try a heading such as "Butte County (Calif.) - Biography" or an historical work under a heading like "Chico (Calif.) -- History."
These can be difficult to find since relatively few articles about this area are listed in major online journal databases, particularly for historical coverage. More recent articles may be available in sources such as LexisNexis or Academic Search, but again you may have to broaden your subject.
These are more plentiful and easier to find. Go to the Newspaper guide and select an online newspaper such as the Chico Enterprise-Record, Chico News & Review, or The Orion. These all have an archival search capability.
Northeast California Collection and Archives:
These collections are located in Special Collections on the third floor. Special Collections is open limited hours during the week. Please check Special Collections for hours and for more information about our collections. Photographs and other digital materials may be found at the CSU Chico Digital Collections page.
World Wide Web:
Since "Chico" is also a word and a common first name, be sure to qualify any web searches to include the entire phrase "Chico California." Try Google Advanced Search.
Chico and Butte County information can be found on the City of Chico and Butte County Government websites.