Budiman, H., M. R. Mulyana, and O. Zuas. “Preparation of calibration standard gas mixtures by primary gravimetric method: a case study on 960 μmol/mol of carbon dioxide in a nitrogen matrix”. Engineering and Applied Science Research, vol. 45, no. 3, Sept. 2018, pp. 173-9, https://ph01.tci-thaijo.org/index.php/easr/article/view/101861.