2026. OPTIMIZING PRODUCTION DECISIONS THROUGH DIFFERENTIAL COST ANALYSIS: A CASE STUDY OF MAKE-OR-BUY STRATEGY IN MANUFACTURING. Jurnal Ilmiah Mahasiswa Akuntansi Universitas Tulungagung. 5, 1 (Aug. 2026), 67–75. DOI:https://doi.org/10.36563/jamanta.v5i1.1660.