Foster, Daniel G.; John Betts; Linda C. Sandelin. (1998). "Style 7 Rock Art and the Martis Complex"(PDF). California Department of Forestry and Fire Protection. Archived from the original(PDF) on 2016-12-21. Retrieved 2019-05-01.
cityofgrassvalley.com
"Prehistoric Context"(PDF). Idaho-Maryland Mine Project, Master Environmental Assessment. cityofgrassvalley.com. June 2006. p. 2. Retrieved 2008-08-15.[dead link]
Foster, Daniel G.; John Betts; Linda C. Sandelin. (1998). "Style 7 Rock Art and the Martis Complex"(PDF). California Department of Forestry and Fire Protection. Archived from the original(PDF) on 2016-12-21. Retrieved 2019-05-01.