When did Barcelona win the treble?

Related questions

1. Is Celtic Irish or Scottish?
2. What age will Messi retire?
3. Has Celtic won 9 in a row?
4. How much do FC Barcelona tickets cost?
5. Is Messi Spanish citizen?
6. How much does a Barcelona season ticket cost?
7. What is the history of El Clasico?
8. How many goals does Messi have in El Clasico?
9. What race were the Celts?
10. Is El Clasico a derby?

Tags

1. #seven
2. #twice
3. #mexican
4. #european
5. #continental
6. #treble
7. #having
8. #barcelona
9. #spanish
10. #clubs
11. #achieved
12. #since
13. #trebles
14. #total
15. #international