File:Ernst Mach square.jpg

Ernst Mach, Austrian physicist and philosopher Date	21 July 2011 Source	http://utf.mff.cuni.cz/Relativity/SCAN/MACH02.JPG Author	Finemann Permission (Reusing this file) CC-BY-SA-3.0

Original filename: https://upload.wikimedihttps://upload.wikimedia.org/wikipedia/commons/9/99/Ernst_Mach_square.jpg