Tidatrut Vichaidid, Thongchai Soodprasert, and Teerasak Verapaspong. “Calibration of HPGe Gamma-Ray Planar Detector System for Radioactivity Standards”. Agriculture and Natural Resources, vol. 41, no. 5, Dec. 2007, pp. 198-02, https://li01.tci-thaijo.org/index.php/anres/article/view/244368.