<https://secure.gravatar.com/avatar/5ada8114f7465316f343d49a040c2162?s=96&amp;d=mm&amp;r=g>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://an-prototype.com/it/aluminum-5052-vs-6061-which-one-is-right-for-your-cnc-project/>