Ambarita, E., Suprayetno, E., Mariana Nkea , A.A. and Kyei, E. 2026. Morphophonemic Allomorphy of the Prefix Um- In Toba Batak: An Extended Generative Morphology Analysis. Journal of Applied Linguistics . 6, 1 (Jul. 2026), 57–74. DOI:https://doi.org/10.52622/joal.v6i1.694.