Kurmarohita, K. (1983) “The Use of Treated Rock Phosphate (Polyphosphate) for Field Crops Grown on Acid Soils of Thailand ”, Thai Agricultural Research Journal, 1(1), pp. 9–15. available at: https://li01.tci-thaijo.org/index.php/thaiagriculturalresearch/article/view/245700 (accessed: 2 October 2026).