Dwi Rohyani, and D. . Ananda. “Knowledge Level Relationship With Community Behavior Concerning Mask Use During The Covid-19 Pandemic In Langkat District, North Sumatera Province”. Jurnal Ilmiah Kesehatan Diagnosis, vol. 16, no. 3, Aug. 2021, pp. 141-6, https://jurnal.stikesnh.ac.id/index.php/jikd/article/view/474.