http://thenounproject.com
http://www.syncfusion.com/downloads/metrostudio/confirmation/146786
http://www.google.com.hk/search?hl=en&q=metro%20style%20icons&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.,cf.osb&biw=1167&bih=1700&wrapid=tlif133248327553710&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=0hRsT4GZDYSTtwfz3azGBg