- Ophir Mining District (Auburn Mining District; Duncan Hill Mining District)
| Pemberton, H. Earl (1983) Minerals of California. Van Nostrand Reinhold Company Inc. Logan, Clarence August (1936), Gold mines of Placer County: California Journal of Mines and Geology, California Division Mines (Report 32): 32(1): 11, 22 Van Nostrand Reinholt Press: 108 |