Source: Alexander Trachtenberg, The History of May Day, 1932;
HTML: for marxists.org in April, 2002.
The International Socialist Congress in Amsterdam calls upon all Social-Democratic Party organizations and trade unions of all countries to demonstrate energetically on May First for the legal establishment of the 8-hour day, for the class demands of the proletariat, and for universal peace. The most effective way of demonstrating on May First is by stoppage of work. The Congress therefore makes it mandatory upon the proletarian organizations of all countries to stop work on May First, wherever it is possible without injury to the workers.