1. The geochemistry of trace elements in marine phosphorite, Part 1. Characteristic abundance and enrichment. In: Bentor, Y.K. (Ed.), Marine Phosphorites;Altschuler;Soc. Econ. Paleontol. Mineral. Spec. Publ.,1980
2. Rare-earth elements in phosphorites of the oceans' bottom;Baturin;Rep. USSR Acad. Sci.,1972
3. Bliskovsky, V.Z., 1983. Veshestveny sostav i obogatimost phosphatnikh rud (Composition and beneficiation of phosphate ores). Nedra Publ. Moscow, 199 pp.
4. Distribution of rare-earth and some trace elements in Tertiary phosphorites from the Senegal Basin and their weathering products;Bonnot-Courtois;Chem. Geol.,1989
5. Bushinsky, G.I., 1969. Old Phosphorites of Asia and Their Genesis. Isr. Prog. Sci. Transl., Jerusalem, 266 pp.