https://www.arduino.cc/en/Reference/HomePage
http://www.prometec.net/arduino-wifi/
https://www.sunfounder.com/wiki/index.php?title=Esp8266_Wifi_Module
http://www.naylampmechatronics.com/blog/22_Tutorial-Lector-RFID-RC522.html
https://www.luisllamas.es/arduino-rfid-mifare-rc522/
https://github.com/miguelbalboa/rfid
https://web.archive.org/web/20151210045625/http://www.nxp.com/documents/leaflet/939775017564.pdf