Evolució de l'aspecte dels mapes de Ordnance Survey des de 1801 <a href="http://blog.ordnancesurvey.co.uk/2012/11/the-evolution-of-ordnance-survey-mapping/">http://blog.ordnancesurvey.co.uk/2012/11/the-evolution-of-ordnance-survey-mapping/</a><br>
<br>Raf<br>