@inproceedings {INPROC-1993-23,
    author = {Frank Leymann},
    title = {{A MOOTOR for accelerating the acceptance of the object paradigm (in German)}},
    booktitle = {Tagungsband des 5. Kolloquiums {\"u}ber ``Software-Entwicklung -- Methoden, Werkzeuge und Erfahrungen'' der Technischen Akademie Esslingen},
    publisher = {Unbekannt},
    institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany},
    type = {Conference Paper},
    month = {September},
    year = {1993},
    language = {German},
    cr-category = {K.1 The Computer Industry},
    department = {University of Stuttgart, Institute of Architecture of Application Systems},
    abstract = {A MOOTOR for accelerating the acceptance of the object paradigm},
    url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-1993-23&engl=1}
 }

@article {ART-1993-05,
    author = {Frank Leymann},
    title = {{Refinement of enquiries in retrieval systems based on the universal relation model}},
    journal = {Information Systems},
    address = {Oxford, UK},
    publisher = {Elsevier Science Ltd.},
    volume = {18},
    number = {2},
    pages = {129--139},
    type = {Article in Journal},
    month = {March},
    year = {1993},
    issn = {0306-4379},
    doi = {10.1016/0306-4379(93)90010-X},
    keywords = {Relational database; universal relation; database semantics; document retrieval; retrieval system; query language; query semantics; database navigation},
    language = {English},
    cr-category = {H.2 Database Management,
                   H.2.3 Database Management Languages,
                   H.3.3 Information Search and Retrieval},
    department = {University of Stuttgart, Institute of Architecture of Application Systems},
    abstract = {Relational Database Management Systems are currently suggested to be used as a
      base for document retrieval systems. This is because commercially available
      relational DBMSs provide effective tools for managing databases and,
      especially, the underlying relational model supports ad hoc queries which are
      characteristic of document retrieval systems. When SQL is directly used for ad
      hoc queries navigation through the underlying database scheme has to be
      provided by the enquirer, which could be very difficult. This article presents
      the achievable simplifications when document retrieval systems will be based on
      the universal relation model. When the search condition of a query is too
      fuzzy, the cardinality of the answer set may become very large. Some retrieval
      systems thus provide the capability of “refining” answer sets; this allows
      referring to an existing answer set when issuing an additional query to reduce
      the number of qualifying tuples. There are two different methods to refine a
      given answer set: one method produces a new query based on the predicates of
      both queries, the other method creates an intermediate answer set based on the
      new query and provides the refined answer set via suitable set manipulations.
      The results are in general different. Focusing on queries on universal relation
      systems, we describe the above problem in more detail and provide criteria
      under which the above methods produce the same result.},
    url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-1993-05&engl=1}
 }

@article {ART-1993-04,
    author = {Wolfgang Altenhuber and Frank Leymann},
    title = {{Unterst{\"u}tzung der Modellierung und Ausf{\"u}hrung von Gesch{\"a}ftsvorg{\"a}ngen im LAN (Support for modeling and execution of business processes in LAN)}},
    journal = {Datenbank Rundbrief},
    publisher = {GI},
    volume = {12},
    pages = {43--44},
    type = {Article in Journal},
    month = {November},
    year = {1993},
    language = {German},
    cr-category = {C.2.0 Computer-Communication Networks, General},
    department = {University of Stuttgart, Institute of Architecture of Application Systems},
    abstract = {Support for modeling and execution of business processes in LAN (in German)},
    url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-1993-04&engl=1}
 }

@book {BOOK-1993-02,
    author = {Hans-Joachim Habermann and Frank Leymann},
    title = {{Repository. Eine Einf{\"u}hrung}},
    publisher = {Oldenbourg Verlag},
    pages = {294},
    type = {Book},
    month = {January},
    year = {1993},
    isbn = {3486222007},
    language = {German},
    cr-category = {H.2.7 Database Administration},
    department = {University of Stuttgart, Institute of Architecture of Application Systems},
    abstract = {Repository: Eine Einf{\"u}hrung},
    url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=BOOK-1993-02&engl=1}
 }