Source: http://www.ecole-valdegrace.sante.defense.gouv.fr/content/download/5258/66167/file/03%20Leyral%20J.%20Echographie%20de%20l%20avant%20au%20Role%201%20quelle%20formation%20pour%20medecin%20unite.Medecine%20et%20Armees%202014-4.309-14..pdf