1) Abrahams, S. C., Jamieson, P. B., and Bernstein, J. L. (1967) Crystal structure of piezoelectric bismuth germanium oxide Bi12GeO20. J. Chem. Phys., 47, 4034–4041.
3) Aurivillius, B. and Sillén, L. G. (1945) Polymorphy of Bi2O3. Nature, 155, 305–306.
4) Batog, V. N., Pakhomov, V. I., Safronov, G. M., and Fedorov, P. M. (1973) Nature of phases with the γ-Bi2O3 structure (sillenite phase). Inorg. Mater. (English translation), 9, 1400–1403.
5) Correia Neves, J. M., Lopes Nunes, J. E., Sahama, Th. G., Lehtinen, M., and von Knorring, O. (1974) Bismuth and antimony minerals in the granite pegmatites of northern Mozambique. Rev. Cien., Geol. Ser. A, 7, 1–37.