K. Foihirun, V. Cholumpai, A. Kritpitakngern, J. Umpunh, W. Inchai, and P. Sukpeng, “Laboratory Examination for Narcotic Drugs and Psychotropic Substances Used among Drug Users in Thailand”, J Health Sci Thai, vol. 15, no. 1, pp. 94–101, May 2019.