BOO, WEI SIANG, and Wan Afnizan Wan Mohamed @ Wan Abd Ghani. “Development of Multiple Concentrations of Phosphorus and Ammonium-Nitrogen Calibration Curve Using Laboratory Resistivity Method at Acidic PH Conditions”. Recent Trends in Civil Engineering and Built Environment, vol. 3, no. 1, Nov. 2021, pp. 374-9, https://publisher.uthm.edu.my/periodicals/index.php/rtcebe/article/view/3290.