Usuaris enriquint col·leccions <a href="http://www.psfk.com/2011/02/citizen-cartography-collectively-generated-archives-of-data-from-historical-maps.html">http://www.psfk.com/2011/02/citizen-cartography-collectively-generated-archives-of-data-from-historical-maps.html </a><br>
<br>Raf<br>