Togatorop, F. “Politeness Strategies Used in the Conversation Between the Students of Finance and Banking Department in Murni Sadar Polytehnic Pematangsiantar”. Journal of English Teaching As a Foreign Language, vol. 5, no. 1, June 2019, pp. 37-48, https://ejournal.uhn.ac.id/index.php/jetafl/article/view/115.