N. M. Saragih, R. Utami, E. Sinaga, and L. Sitepu, “THE INFLUENCE OF HUMAN RELATIONS AND THE PHYSICAL WORK ENVIRONMENT ON MORALE IN EMPLOYEES OF THE REGIONAL REVENUE AGENCY DELI SERDANG”, Jurnal Ekonomi, vol. 11, no. 03, pp. 208–215, Oct. 2022.