Durham's Place-Names of California's North Coast: Includes Del Norte, Humboldt, Lake, Mendocino and Trinity Counties (Durham) 2000 (F 867.5 D87 2000 - Humboldt County Collection)
Klamath Places Database (Humboldt State University - Advanced Spatial Analysis Facility) Includes all of the official USGS place names for the Klamath Basin in addition to many more local place names, gauging stations and others. The database is searchable by county, watershed, category and name. Each place name is linked to a location map.
Place Names of Humboldt County, California: A Compendium, 1542-1992 (Turner) 1993 (F 868 H8 T87 1993 - Reference and Humboldt County Collection) The major compilation of Humboldt County place names containing references to futher sources of information on specific place names.
Trinity County Historic Sites (Trinity County Historical Society) 1981 (F 868 T6 T76 Humboldt County Collection and bookstacks) Includes historical notes on approximately 500 historical sites and place names in Trinity County. Grouped into seven geographical areas.