The philosophy of Athletic Club consists exclusively in fielding players either born or raised in the Basque Country (Euskal Herria).
Athletic Bilbao: The Pride Of The Basque Country - El Arte Del Futbol
Athletic Bilbao's methods provide lessons for Premier League clubs, Football News
Athletic Bilbao's Basque-only 'philosophy' – and why some are calling for change - The Athletic
Fred Pentland: Athletic Bilbao's English coach who changed the face of Spanish football - BBC Sport
Why the Athletic Club Bilbao is a soccer treasure?
Inside Athletic Bilbao: the football club playing by their own rules
Philosophy and Values of the Athletic Bilbao footbal team
Athletic Bilbao's Basque-only Policy: old school Romanticism or sheer Discrimination?, by Jürn De Baets
ATHLETIC CLUB - Bilbao Turismo
Is Athletic Bilbao's 110-year unwritten rule about to change? - Football
The year of two Copa del Rey finals: Athletic Bilbao loses first, but has second chance against FC Barcelona
This is Athletic Bilbao: the club whose loyalty to local talent is not negotiable, Athletic Bilbao
Athletic seals its entry to the Super Cup and a European match