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http://datos.bancomundial.org/indicador/EG.USE.COMM.FO.ZS
. Last visit: 22th November, 2017
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https://www.endesa.com/content/dam/enel-es/home/inversores/infoeconomicafinanciera/informesanuales/documentos/2013/Sostenibilidad%202013.pdf
. Last visit: 22th November, 2017
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https://twenergy.com/a/el-largo-viaje-de-la-electricidad-211
. Last visit: 22th November, 2017
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http://www.sciencedirect.com/science/article/pii/S1364815212002095
5. del Viento G (2017) Wind-hydro-pumped station of El Hierro.
http://www.goronadelviento.es/index.php
. Last visit: 22th November, 2017