Zhang, C., and Y. Li. “RFID Localization System Based on K-Nearest Neighbor Algorithm and Extreme Learning Machine Algorithm With Virtual Reference Tags”. American Scientific Research Journal for Engineering, Technology, and Sciences, vol. 54, no. 1, Apr. 2019, pp. 82-91, https://www.asrjetsjournal.org/index.php/American_Scientific_Journal/article/view/4766.