http://hub.pirelli.com/resources/js/libs/srcset-polyfill.min.js
http://www.transindex.ro/uj/js/srcset.min.js
https://www.internetx.com/fileadmin/template/js/srcset.min.js
http://www.stabilus.com/fileadmin/templates/js/srcset.min.js
http://flexwork.io/js/srcset/srcset.min.js