License specification of some of the images published in the website www.altermia.es
http://www.flickr.com/photos/nikonvscanon/3166595271/
http://www.flickr.com/photos/officenow/2630715573/
http://www.flickr.com/photos/drstarbuck/830058268/
http://www.flickr.com/photos/sondyaustin/3216120791/
http://www.flickr.com/photos/jimmyharris/2798647691/
http://www.flickr.com/photos/ontariopowergeneration/413709625/
http://www.flickr.com/photos/therussiansarehere/3054068457/
http://www.flickr.com/photos/therussiansarehere/3338246749/
http://www.flickr.com/photos/rgomez74/3056844531/
http://www.flickr.com/photos/langalex/3546825820/
http://www.flickr.com/photos/grendelkhan/106679350/
http://www.flickr.com/photos/adders/3096778384/
http://www.flickr.com/photos/pikturewerk/2270214139
http://commons.wikimedia.org/wiki/File:Fresnel_reflectors_ausra.jpg
