Ries, Eric. The Lean Startup. Random House, Inc..

http://www.flickr.com/photos/san_drino/1454922072 Ries, Eric. The Lean Startup. Random House, Inc..

http://www.flickr.com/photos/91262622@N02/10482638016

http://upload.wikimedia.org/wikipedia/commons/thumb/6/66/Einstein_1921_by_F_Schmutzer.jpg

Source: Juan Lucena, Colorado School of Mines

http://www.flickr.com/photos/twitchcraft/3223196785

http://embraceblog.org/photos-from-the-field/