Gem hunter's guide
by
Russell P. MacFall
1975, T. Y. Crowell
Gold placers of California
by
Charles Scott Haley
1923
Placer mining for gold in California
by
Charles Volney Averill
1946
The rock-hound's book
by
Seymour Simon
1973
1994 gold prospector's mining guide
by
Gold Prospectors Association of America
1994