
Actually written by E. F. Schumacher in a 1973 essay titled "Small is Beautiful" which appeared in The Radical Humanist: volume 37, p. 22 http://books.google.com/books?id=oA0IAQAAIAAJ&q=%22more+violent%22#search_anchor. Earliest published source found on Google Books attributing this to Einstein is BMJ: The British Medical Journal, volume 319, 23 October 1999, p. 1102 http://books.google.com/books?id=bQk7AQAAIAAJ&q=%22more+violent%22#search_anchor. It was attributed to Einstein on the internet somewhat before that, for example in this 1997 post http://groups.google.com/group/alt.weemba/msg/2bbf56ab8f4f757d?hl=en.
Misattributed