Purba, Christian Neni. “Politeness Strategies Used by Speakers of Sahap Simalungun (SS) in Kecamatan Raya”. Journal of English Teaching as a Foreign Language 1, no. 2 (December 30, 2015): 1-16. Accessed May 19, 2024. https://ejournal.uhn.ac.id/index.php/jetafl/article/view/177.