Riveros, O. A., J. G. Romero, and J. F. Herrera. “Implementation of the K -Neighbors Technique in a Recommender Algorithm for a Purchasing System Using NFC and Android”. INGE CUC, vol. 13, no. 1, Jan. 2017, pp. 9-18, doi:10.17981/ingecuc.13.1.2017.01.