Claim: The longest-serving president was  Josef Duffner, (March 20, 1930-March 04,1933), while the shortest-serving president was Ferdinand Kopf (January05,1919-October 07, 1921).
Evidence: Ferdinand Kopf, Zentrum 5 January 1919 – 7 October 1921 Josef Duffner, Zentrum 20 March 1930 – 4 March 1933 4 May 1923 – 20 March 1930 Eugen Baumgartner, Zentrum