Alfonso X was the king of Castile, León and Galicia from 1252 until his death. He established the form of modern Castilian Spanish.
Alfonso X. (2013). The Biography Channel website. Retrieved 06:23, Jun 19, 2013, from http://www.biography.com/people/alfonso-x-9180827.
Alfonso X. [Internet]. 2013. The Biography Channel website. Available from: http://www.biography.com/people/alfonso-x-9180827 [Accessed 19 Jun 2013].
"Alfonso X." 2013. The Biography Channel website. Jun 19 2013, 06:23 http://www.biography.com/people/alfonso-x-9180827.
"Alfonso X," The Biography Channel website, 2013, http://www.biography.com/people/alfonso-x-9180827 [accessed Jun 19, 2013].
"Alfonso X," The Biography Channel website, http://www.biography.com/people/alfonso-x-9180827 (accessed Jun 19, 2013).
Alfonso X [Internet]. The Biography Channel website; 2013 [cited 2013 Jun 19] Available from: http://www.biography.com/people/alfonso-x-9180827.
Alfonso X, http://www.biography.com/people/alfonso-x-9180827 (last visited Jun 19, 2013).
Alfonso X. The Biography Channel website. 2013. Available at: http://www.biography.com/people/alfonso-x-9180827. Accessed Jun 19, 2013.