P. T. H. . Tham, P. T. P. Thuc, P. T. H. . Giang, and N. T. . Tam, “The Current Status of Secondary School Teacher’s Perception of Happiness in Nam Dinh Province during the Implementation Period of the 2018 General Education Program”, AJSSMS, vol. 9, no. 3, pp. 60–64, Jul. 2022.