| India | | |
| Rao, J. S. R. K., Naidu, B. V. & Rao, K. V. (1979): Ore microscopic, x-ray and trace elemental data on manganese ores from Sandur, Karnataka, India. Acta Mineralogica-Petrographica 24, 91-97. | | Japan | | |
| Watanabe, T. (1959) Mineralogical Journal, 2, 6, 408-421 | | USA | | |
| www.deq.state.mi.us/documents/deq-glm-rcim-geology-Minerals_Found_In_Michigan.Pdf. |
|