1. Thomas, E.P.: Product tags, systems, and methods for crowdsourcing and electronic article surveillance in retail inventory management, March 12 2019. US Patent 10,229,386
2. Abbott, J.J., Okamura, A.M.: Effects of position quantization and sampling rate on virtual-wall passivity. IEEE Trans. Rob. 21(5), 952–964 (2005)
3. Ordonez, C., Collins, E.G., Jr., Selekwa, M.F., Dunlap, D.D.: The virtual wall approach to limit cycle avoidance for unmanned ground vehicles. Robot. Auton. Syst. 56(8), 645–657 (2008)
4. Norman, T.L.: Integrated security systems design: concepts, specifications, and implementation. Elsevier (2011)
5. Tan, S.: Intelligent entrance guard lock system based on remote control, 2016. US Patent CN106355724A (2016)