1. R.G. Breuer Extractive Metallurgy of Aluminum, Vol. 1 Alumina, Interscience Publishers (1963), 133 157
2. Adamson Extractive Metallurgy of Aluminum, Vol. 1 Alumina, Interscience Publishers (1963), 23 57
3. T. Oku K. Yamada Light Metals 1971, 31 45
4. M.G. Leiteizen Tzvetnie Metalli, 1972, 37 40