Khusna, Arfiani Nur, et al. “Penerapan User-Based Collaborative Filtering Algorithm”. MATRIK : Jurnal Manajemen, Teknik Informatika Dan Rekayasa Komputer, vol. 20, no. 2, May 2021, pp. 293-04, https://doi.org/10.30812/matrik.v20i2.1124.