Hardani, Dian Nova Kusuma, et al. “Identify The Authenticity of Rupiah Currency Using K Nearest Neighbor (K-NN) Algorithm”. Jurnal Ilmiah Teknik Elektro Komputer Dan Informatika, vol. 5, no. 1, July 2019, pp. 1-7, doi:10.26555/jiteki.v5i1.13324.