อรุณศรีมรกต สยาม. “ISO 50001:2001 (ENERGY MANAGEMENT SYSTEMS)”. Research Journal Phranakhon Rajabhat : Science and Technology 13, no. 2 (July 10, 2018): 197–206. accessed September 10, 2026. https://li01.tci-thaijo.org/index.php/PRRJ_Scitech/article/view/119064.