A. Napitupulu, R. Sembiring, C. Lubis, S. Manoeroen, and H. Siregar, “The Micro Erythrocyte Sedimentation Rate (ESR) Among Chiidren of the Tobacco Plantation Laborers in North Sumatra”, PI, vol. 19, no. 11-12, pp. 302-7, Jun. 2017.