M. Br. Marpaung, Siti Aisyah Hanim, and Maulidawati, “Illocutionary Acts of Speech in the Customary Marriage of the Toba Batak Community on the Use of Umpasa in Aek Song-Songan District, Asahan Regency”, JPLED, vol. 6, no. 1, Apr. 2026.