<http://www.w3.org/1999/02/22-rdf-syntax-ns#first>
<http://ghk.h-cdn.co/assets/cm/15/12/550951a813814-pebble-art-step-3-azpc4k-de.jpg>
<http://www.goodhousekeeping.com/home/craft-ideas/how-to/a25190/monogram-pebble-project/>