Article: The European powers continued to pursue diplomatic avenues. The representatives of the four neutral Great Powers—the United Kingdom, France, Austria and Prussia—met in Vienna, where they drafted a note that they hoped would be acceptable to both the Russians and the Ottomans. The peace terms arrived at by the four powers at the Vienna Conference were delivered to the Russians by the Austrian Foreign Minister Count Karl von Buol on 5 December 1853. The note met with the approval of Nicholas I; however, Abdülmecid I rejected the proposal, feeling that the document's poor phrasing left it open to many different interpretations. The United Kingdom, France, and Austria united in proposing amendments to mollify the Sultan, but the court of St. Petersburg ignored their suggestions.:143 The UK and France then set aside the idea of continuing negotiations, but Austria and Prussia did not believe that the rejection of the proposed amendments justified the abandonment of the diplomatic process.

Question: What European powers met in Vienna for a conference?
United Kingdom, France, Austria and Prussia