Oonsiri, P. “IsoCal Evaluation for Isocentric Performance Check of Varian Linacs With C-Series and TrueBeam”. Journal of Thai Association of Radiation Oncology, vol. 25, no. 2, Oct. 2019, pp. 19-27, https://he01.tci-thaijo.org/index.php/jtaro/article/view/209546.