<http://schema.org/url>
<http://thenextweb.com/lifehacks/2012/06/22/nifty-google-search-lets-you-filter-out-search-results-youve-already-visited/>
<http://thenextweb.com/lifehacks/2012/06/22/nifty-google-search-lets-you-filter-out-search-results-youve-already-visited/>