Ambarita, E., E. Suprayetno, A. A. . Mariana Nkea, and E. . Kyei. “Morphophonemic Allomorphy of the Prefix Um- In Toba Batak: An Extended Generative Morphology Analysis”. Journal of Applied Linguistics, vol. 6, no. 1, July 2026, pp. 57-74, doi:10.52622/joal.v6i1.694.