Fonti a stampaLife and inventions of Richard Roberts / Rev. Dr. Richard L. Hills, 2002
A (drawing) portrait of Richard Roberts (1789-1864), a British engineer. [Unknown authorUnknown author / Roe JW (1916). English and American Tool Builders. (https://books.google.com/books?id=X-EJAAAAIAAJ&printsec=titlepage#v=onepage) -- Public domain -- http://commons.wikimedia.org/wiki/File:Roberts Richard from Roe 1916.png]