Minimalist Silk icon set with some customization made for Calibre. Silk by Mark James (
http://www.famfamfam.com/lab/icons/silk/), additional icons from Fugue by Yusuke Kamiyamane (
http://p.yusukekamiyamane.com/).
Best viewed with Icon size: Small, and Show text: Never
Creative Commons Attribution 3.0 License