References
- Turkish State Planning Organisation Report No. OPT 2123-0IK:327 ( March 1988 ).
- P. A. Lyday . “ Boron, ” U.S. Bureau of Mines , Preprint from Bulletin 675 Mineral Facts and Problems (1985 ed.).
- Istanbul Minerals and Metals Exporters Association , Monthly Bulletin ( Dec . 1989 ).