Shadlov А. И., and Dmitrienko Г. В. “Optimization of the Procedure of Confirming the Competence of Testing Laboratories That Perform a Special Assessment of Working Conditions”. Vestnik IzhGTU Imeni M.T. Kalashnikova, vol. 19, no. 2, June 2016, pp. 94-97, https://izdat.istu.ru/index.php/vestnik/article/view/3242.