If you want to understand how the PID (the reader) and the PICC (the tag) interact:
- AN10833 MIFARE Type Identification Procedure
- AN10834 MIFARE ISO/IEC 14443 PICC Selection
- AN10927 MIFARE product and handling of UIDs - helps to understand how the full tag's UID gets read.
- http://privat.bahnhof.se/wb736562/rfid/Card%20dokuments/Security_Analysis_of_RFID_Tags-2008.pdf - interesting security analysis
- https://www.nxp.com/docs/en/data-sheet/MF1S50YYX_V1.pdf - MIFARE Classic documentation
- https://learn.adafruit.com/adafruit-pn532-rfid-nfc/ndef - Adafruit on NDEF protocol
- https://www.nxp.com/docs/en/user-guide/141520.pdf - User Guide