CC BY 3.0
<a rel="nofollow" class="external text" href="http://imslp.org/index.php?title=Preludes%2C_Op.28_%28Chopin%2C_Fr%C3%A9d%C3%A9ric%29&amp;action=historysubmit&amp;diff=756504&amp;oldid=756372">Initially uploaded by Ivan Ilić to imslp.org</a> (<a rel="nofollow" class="external text" href="http://imslp.org/wiki/User:Ivan_Ilic">his User page at IMSLP</a>)