@techreport{iiasa50,
           month = {August},
            type = {IIASA Planning Conference},
           title = {Proceedings of IIASA Planning Conference on Urban and Regional Systems, July 30-August 1, 1973},
         address = {IIASA, Laxenburg, Austria},
       publisher = {PC-73-004},
            year = {1973},
             url = {https://pure.iiasa.ac.at/id/eprint/50/},
          author = {IIASA Urban Project, {}}
}