Article 231 of the Treaty of Versailles places the blame of the war solely on Germany and her allies. This is the quote:
The Allied and Associated Governments affirm and Germany accepts the responsibility of Germany and her allies for causing all the loss and damage to which the Allied and Associated Governments and their nationals have been subjected as a consequence of the war imposed upon them by the aggression of Germany and her allies.
Many historians who use the war guilt methodology have different views as to what countries in question were to blame for provoking the world war. My professor explained that he has read books arguing that the weight the blame is on Russia for siding with Serbia in the Balkan Wars. The First World War could then be viewed as the Third Balkan War. Another popular view is that Great Britain was at fault. Had she allied with Germany and put aside her fears of Germany's growing navy, there would have been no war. Great Britain was itching for a war against Germany because there was a great fear that Germany would destroy the balance of power and replace it with a German hegemony.
