@misc{BERNHOLDKALINGLELLEK2011,
  author    = {BERNHOLD, T. and KALING, N. and LELLEK, M.},
  title     = {Measurement of productivity of property services: an empiric analysis of the status quo, XXI. International RESER Conference, Hamburg, 07.09.-10.09.2011},
  year      = {2011},
  language  = {en}
}
@incollection{BERNHOLDKALINGLELLEK2012,
  author    = {BERNHOLD, T. and KALING, N. and LELLEK, V.},
  title     = {Productivity Measurement Model - A Holistic Approach For Services},
  series = {Proceedings of the 11th EuroFM Research Symposium, 24.-25. May 2012 in Copenhagen, Denmark, IN: JUNGHANS, A.; JENSEN, P. A. (Editors)},
  booktitle = {Proceedings of the 11th EuroFM Research Symposium, 24.-25. May 2012 in Copenhagen, Denmark, IN: JUNGHANS, A.; JENSEN, P. A. (Editors)},
  publisher = {Polyeknisk Forlag},
  address   = {Lyngby},
  pages     = {20 -- 30},
  year      = {2012},
  language  = {en}
}
@incollection{BERNHOLDKALINGLELLEK2011,
  author    = {BERNHOLD, T. and KALING, N. and LELLEK, M.},
  title     = {Measurement of productivity of property services - an empiric analysis of the status quo},
  series = {GANZ, W.; KIRCHERER, F.; SCHLETZ, A. (Hrsg.); Productivity of Services NextGen - Beyond Output/Input},
  booktitle = {GANZ, W.; KIRCHERER, F.; SCHLETZ, A. (Hrsg.); Productivity of Services NextGen - Beyond Output/Input},
  edition   = {1. Aufl.},
  publisher = {Fraunhofer Verlag},
  address   = {Stuttgart},
  isbn      = {978-3-8396-0297-3},
  pages     = {190 -- 191},
  year      = {2011},
  language  = {en}
}
@article{BECKERBERNHOLDBEVERUNGENetal.2012,
  author    = {BECKER, J. and BERNHOLD, T. and BEVERUNGEN, D. and KALING, N. and KNACKSTEDT, R. and LELLEK, V. and RAUER, H.},
  title     = {Construction of Productivity Models - A Tool-Supported Approach in the Area of Facility Management},
  series = {Enterprise Modelling and Information Systems Architectures},
  journal   = {Enterprise Modelling and Information Systems Architectures},
  number    = {Vol. 7, No. 1},
  pages     = {28 -- 43},
  year      = {2012},
  language  = {en}
}