Purba, Rohan Kristini, Dendy Frans Gunawan Hutagalung, Ebenezer Maston Sinaga, Agustina Sidabutar, and Mesran Mesran. 2022. “Optimalisasi Dalam Penentuan Keputusan Level Pemberlakuan Pembatasan Kegiatan Masyarakat (PPKM) Menerapkan Metode Preference Selection Index”. Journal of Information System Research (JOSH) 3 (2), 63-75. https://doi.org/10.47065/josh.v3i2.1247.