P. Narot, N. Prohmchum, T. Prasertcha-roensuk, J. Rachvijit, T. Bunterm, and T. Bunterm, “An evaluation of the effectiveness of non-formal education programs: a case study of the Northeastern Region.(Thai)”, Asia Pac J Sci Technol, vol. 11, no. 2, pp. 135–147, Apr. 2017.