@INPROCEEDINGS{hamacher01d,
    author = {N. Hamacher and J. Marrenbach and K.-F. Kraiss},
    title = {Formal Usability Evaluation of Interactive Systems},
    booktitle = {8th IFAC/IFIP/IFORS/IEA Symposium on Analysis, Design, and Evaluation of Human Machine     Systems 2001},
    year = {2001},
    editor = {G. Johannsen},
    pages = {577-581},
    address = {Kassel},
    month = {September},
    publisher = {Elsevier Science},
}