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ICAO airport code - Wikipedia
Lists of airports by IATA and ICAO code - Wikipedia
List of airports by ICAO code: A - Wikipedia
International Civil Aviation Organization - Wikipedia
IATA airport code - Wikipedia
International Civil Aviation Organization airport code
IATA and ICAO: a guide to airline and airport codes - AeroTime
ICAO code - Wikipedia
Airport codes – Travel guide at Wikivoyage
ICAO Codes explained - Key.Aero