@incollection{iiasa4227,
          number = {3},
          series = {Vienna Circle Institute Yearbook},
       booktitle = {The Foundational Debate Complexity and Constructivity in Mathematics and Physics},
          editor = {W. DePauli-Schimanovich and E. K{\"o}hler and F. Stadler},
           title = {Hans Hahn and the foundational debate},
       publisher = {Springer},
            year = {1995},
         journal = {Vienna Circle Institute Yearbook: The Foundational Debate Constructivity and Complexity in Mathematics and Physics},
           pages = {235--245},
             url = {http://www.univie.ac.at/ivc/publikat/index.htm},
            isbn = {978-94-017-3327-4},
          author = {Sigmund, K.}
}