sembiring, Andes Stefen. “Pengembangan Bisnis Tour and Travel Di Masa Pandemi COVID 19 ( Studi Kasus : Pt. Milala Wisata)”. Jurnal Ilmiah Teknik Industri Prima (JURITI PRIMA) , vol. 4, no. 2, July 2021, doi:10.34012/juritiprima.v4i2.1732.