Relevant Cost Analysis in Decision Making (Producing Own or Buying From Outside) at Old Bakery: Analisis Biaya Relevan Dalam Pengambilan Keputusan (Memproduksi Sendiri Atau Membeli Dari Luar) Pada Old Bakery. j.Perilaku Bisnis Kontemporer [Internet]. 2025 Nov. 17 [cited 2026 May 7];2(3):155-62. Available from: https://journal.sumaterascientist.id/index.php/JUBIKO/article/view/53