- Biblioteca Nacional: http://www.bne.es/en/Colecciones/Cervantes/
- Instituto Cervantes Chicago: http://chicago.cervantes.es/en/default.shtm
- Creative Commons: http://search.creativecommons.org/
- Wordreference: http://www.wordreference.com/
- QuizRevolution:http://www.quizrevolution.com