1. O.A. Songina, Rare Metals, 3rd ed., Israel Program for Scientific Translations, IPST Cat. No. 5654, UDC 66.2/8 (Springfield, VA: Clearinghouse for Federal Scientific and Technical Information, 22151, 1970).
2. G. Vagner and V. Gitzen, Uspekhi Khimii, 22(1) (1953), p. 106.
3. D.A. Kramer, Gallium and Gallium Arsenide: Supply and Technology, and Uses, USBM IC 9208, 1988.
4. G.M. Swinkels and J.E. Litz, “The Apex Project: Development of a Primary Gallium and Germanium Producer,” presentation at the SME Annual Meeting, New Orleans, LA (March 2–6, 1986).
5. M.P. Wardell and C.F. Davidson, JOM, 39(6) (1987), pp. 39–41.