\newcommand{\etalchar}[1]{$^{#1}$}
\begin{thebibliography}{SWBM89}

\bibitem[ACC81]{ACC81a}
M.P. Atkinson, K.J. Chisholm, and W.P. Cockshott.
\newblock PS-Algol: An Algol with a Persistent Heap.
\newblock {\em ACM SIGPLAN Notices}, 17(7), July 1981.

\bibitem[BJM{\etalchar{+}}89]{BJMSV89}
A.~Borgida, M.~Jarke, J.~Mylopoulos, J.W. Schmidt, and Y.~Vassiliou.
\newblock The Software Development Environment as a Knowledge Base Management
  System.
\newblock In J.W. Schmidt and C.~Thanos, editors, {\em Foundations of Knowledge
  Base Management}, Topics in Information Systems. Springer-Verlag, 1989.

\bibitem[BJS86]{BJS86}
S.~B\"ottcher, M.~Jarke, and J.W. Schmidt.
\newblock Adaptive Predicate Managers in Database Systems.
\newblock In {\em Proc. of the 12th International Conference on VLDB}, Kyoto,
  1986.

\bibitem[BMSW89]{BMSW89}
A.~Borgida, J.~Mylopoulos, J.W. Schmidt, and I.~Wetzel.
\newblock Support for Data-Intensive Applications: Conceptual Design and
  Software Development.
\newblock In {\em Proc. of the 2nd Workshop on Database Programming Languages,
  Salishan Lodge, Oregon}, June 1989.

\bibitem[CM84]{CoMa84}
G.~Copeland and D.~Maier.
\newblock Making Smalltalk a database system.
\newblock In {\em ACM-SIGMOD International Conference on Management of Data},
  pages 316--325, Boston, Ma., June 1984.

\bibitem[DCBM89]{DCBM89}
A.~Dearle, R.~Connor, F.~Brown, and R.~Morrison.
\newblock Napier88 -- A Database Programming Language?
\newblock In {\em Proc. of the 2nd Workshop on Database Programming Languages,
  Salishan Lodge, Oregon}, June 1989.

\bibitem[Dea89]{Dea89}
A.~Dearle.
\newblock Environments: a flexible binding mechanism to support system
  evolution.
\newblock In {\em Proc. HICSS-22, Hawaii}, volume~II, pages 46--55, January
  1989.

\bibitem[Gro87]{PPRG87}
Persistent Programming~Research Group.
\newblock PS-algol Reference Manual.
\newblock PPRR 12-87, University of Glasgow, Dept. of Comp. Science, 1987.

\bibitem[JGL{\etalchar{+}}88]{JGLR88}
W.~Johannsen, L.~Ge, W.~Lamersdorf, K.~Reinhard, and J.W. Schmidt.
\newblock Database Application Support in Open Systems: Language Support and
  Implementation.
\newblock In {\em Proc. IEEE 4th Int. Conf. on Data Engineering}, Los Angeles,
  USA, February 1988.

\bibitem[JLRS88]{DURESS88}
W.~Johannsen, W.~Lamersdorf, K.~Reinhardt, and J.W. Schmidt.
\newblock The DURESS Project: Extending Databases into an Open Systems
  Architecture.
\newblock In {\em Advances in Database Technology -- EDBT 88}, volume 303 of
  {\em Lecture Notes in Computer Science}, pages 616--620. Springer-Verlag,
  1988.

\bibitem[MRS89]{DAIDA4}
F.~Matthes, A.~Rudloff, and J.W. Schmidt.
\newblock Data- and Rule-Based Database Programming in DBPL.
\newblock Esprit Project 892 WP/IMP 3.b, Fachbereich Informatik, Johann
  Wolfgang Goethe-Universit\"at, Frankfurt, West Germany, March 1989.

\bibitem[MS89]{MaSc89}
F.~Matthes and J.W. Schmidt.
\newblock The Type System of DBPL.
\newblock In {\em Proc. of the 2nd Workshop on Database Programming Languages,
  Salishan Lodge, Oregon}, pages 255--260, June 1989.

\bibitem[NS87]{NiSc89}
P.~Niebergall and J.W. Schmidt.
\newblock Integrated DAIDA Environment, Part 2: DBPL-Use: A Tool for
  Language-Sensitive Programming.
\newblock DAIDA Deliverable WP/IMP-2.c, Fachbereich Informatik, Johann Wolfgang
  Goethe-Universit\"at, Frankfurt, West Germany, 1987.

\bibitem[SBK{\etalchar{+}}88]{DAIDA2}
J.W. Schmidt, M.~Bittner, H.~Klein, H.~Eckhardt, and F.~Matthes.
\newblock DBPL System: The Prototype and its Architecture.
\newblock Esprit Project 892 WP/IMP 3.2, Fachbereich Informatik, Johann
  Wolfgang Goethe-Universit\"at, Frankfurt, West Germany, November 1988.

\bibitem[Sch77]{Schm77}
J.W. Schmidt.
\newblock Some High Level Language Constructs for Data of Type Relation.
\newblock {\em ACM Transactions on Database Systems}, 2(3), September 1977.

\bibitem[SEM88]{SEM88}
J.W. Schmidt, H.~Eckhardt, and F.~Matthes.
\newblock DBPL Report.
\newblock DBPL-Memo 111-88, Fachbereich Informatik, Johann Wolfgang
  Goethe-Universit\"at, Frankfurt, West Germany, 1988.

\bibitem[SGLJ89]{SGLJ89}
J.W Schmidt, L.~Ge, V.~Linnemann, and M.~Jarke.
\newblock Integrated Fact and Rule Management Based on Database Technology.
\newblock In J.W. Schmidt and C.~Thanos, editors, {\em Foundations of Knowledge
  Base Management}, Topics in Information Systems. Springer-Verlag, 1989.

\bibitem[SWBM89]{SWBM89}
J.W. Schmidt, I.~Wetzel, A.~Borgida, and J.~Mylopoulos.
\newblock Database Programming by Formal Refinement of Conceptual Designs.
\newblock {\em IEEE -- Data Engineering}, September 1989.

\bibitem[Tea88]{DAIDA88}
DAIDA Team.
\newblock Towards KBMS for Software Development: An Overview of the DAIDA
  Project.
\newblock In {\em Advances in Database Technology, EDBT '88}, volume 303 of
  {\em Lecture Notes in Computer Science}, pages 572--577. Springer-Verlag,
  1988.

\bibitem[Wir83]{Wirt83}
N.~Wirth.
\newblock {\em Programming in Modula-2}.
\newblock Springer-Verlag, 1983.

\bibitem[WNS89]{DAIDA3}
I.~Wetzel, P.~Niebergall, and J.W. Schmidt.
\newblock A Mapping Assistant for Database Program Development.
\newblock Esprit Project 892 WP/IMP 1.d, Fachbereich Informatik, Johann
  Wolfgang Goethe-Universit\"at, Frankfurt, West Germany, March 1989.

\end{thebibliography}