(https://www.forummontefrio.es/forum/proxy.php?request=http%3A%2F%2Fimg200.imageshack.us%2Fimg200%2F3069%2Fintercambio.jpg&hash=1c8b8224288a5000d24f350322094c99d83c4920)
(https://www.forummontefrio.es/forum/proxy.php?request=http%3A%2F%2Fimg9.imageshack.us%2Fimg9%2F4849%2Fiintercanbio1.jpg&hash=f9b51a0b4971961ffac58ae0a53d47909c86505d)
(https://www.forummontefrio.es/forum/proxy.php?request=http%3A%2F%2Fimg9.imageshack.us%2Fimg9%2F1862%2Fiintercambio2.jpg&hash=4c764157459eeae01761dedd9008997ca718c3b9)
http://www.montefrio.org/impresos/intercambio.pdf