Não informado. (1947). Information Circular. State of California, Department of Natural Resources, Division of Mines.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Information Circular. San Francisco, Calif: State of California, Department of Natural Resources, Division of Mines, 1947.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Information Circular. State of California, Department of Natural Resources, Division of Mines, 1947.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.