Knowledge Level Relationship With Community Behavior Concerning Mask Use During The Covid-19 Pandemic In Langkat District, North Sumatera Province. DJIK [Internet]. 31 Agustus 2021 [dikutip 12 Oktober 2026];16(3):141-6. Tersedia pada: https://ojs.institutnh.ac.id/index.php/jikd/article/view/474