Terms and conditions for the use of images supplied by Alvaro Catalán de Ocón:

Every appearance of these images must be accompanied by the correct caption, provided by Alvaro Catalán de Ocón.

Image integrity must be maintained, in that each image must be shown with no overprinting or changes to proportions or ratio.

Please ensure that a copy of the article in which this image is reproduced is sent to the Communication Department of Alvaro Catalán de Ocón, Calle Conde de Vistahermosa 5 1ºD, 28019 Madrid (Spain) or email a copy to Denisa Iancu: denisa@acdo.es