Influence of rainfall and ancient landslide deposits on recent landslides (1950 - 71) in urban areas of Contra Costa County, California jointly supported by the U.S. Geological Survey and the Department of Housing and Urban Development as part of a program to develop earth-science information in a form applicable to land-use planning and decisionmaking - Nilsen, Tor Helge 1941-; Turner, Barbara L. (Geological Survey bulletin, 1975)