\newcommand{\etalchar}[1]{$^{#1}$}
\begin{thebibliography}{MBCD89}

\bibitem[ABC{\etalchar{+}}83]{ABCCM83}
M.P. Atkinson, P.J. Bailey, K.J. Chisholm, W.P. Cockshott, and R.~Morrison.
\newblock An approach to persistent programming.
\newblock {\em Computer Journal}, 26(4), November 1983.

\bibitem[ABM88]{ABM88}
M.P. Atkinson, P.~Buneman, and R.~Morrison, editors.
\newblock {\em Data Types and Persistence}.
\newblock Topics in Information Systems. Springer-Verlag, 1988.

\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[Car88]{Card88b}
L.~Cardelli.
\newblock Types for data-oriented languages.
\newblock In {\em Advances in Database Technology, EDBT '88}, volume 303 of
  {\em Lecture Notes in Computer Science}, pages 1--15. Springer-Verlag, 1988.

\bibitem[CD87]{CDeW88}
M.J. Carey and D.J~. DeWitt.
\newblock An overview of the {EXODUS} project.
\newblock {\em Database Engineering, Special Issue on Extensible Database
  Systems}, 10(2), June 1987.

\bibitem[CDRS86]{CDJS86}
M.~Carey, D.~DeWitt, J.~Richardson, and E.~Sheikta.
\newblock Object and file management in the {EXODUS} extensible database
  system.
\newblock In {\em Proc. of the 12th VLDB Conference}, Kyoto, Japan, August
  1986.

\bibitem[Cop85]{Copp85}
M.~Coppo.
\newblock A ccompleteness theorem for recursively defined types.
\newblock In G.~Goos and J.~Hartmanis, editors, {\em Automata, Languages and
  Programming, 12th Colloquium}, volume 194 of {\em Lecture Notes in Computer
  Science}, pages 120--129. Springer, July 1985.

\bibitem[Cou83]{Cour83}
B.~Courcelle.
\newblock Fundamental properties of infinite trees.
\newblock {\em Theoretical Computer Science}, 25:95--169, 1983.

\bibitem[DM82]{DaMi82}
L.~Damas and R.~Milner.
\newblock Principal type-schemes for functional programs.
\newblock In {\em Proc. 9th ACM Symposium on Principles of Programming
  Languages}, pages 207--212, 1982.

\bibitem[HFLP89]{HFLP89}
L.M. Haas, J.C. Freytag, G.M. Lohmann, and H.~Pirahesh.
\newblock Extensible query processing in {Starburst}.
\newblock In {\em ACM-SIGMOD International Conference on Management of Data},
  pages 377--388, Portland, Oregon, 1989.

\bibitem[HMT88]{HMT88}
R.~Harper, R.~Milner, and M.~Tofte.
\newblock The definition of {Standard ML}.
\newblock LFCS Report Series ECS-LFCS-88-62, Department of Computer Science,
  University of Edinburgh, August 1988.

\bibitem[KC86]{KhCo86}
S.~Khoshafian and G.~Copeland.
\newblock Object identity.
\newblock In {\em Proc. of 1st Int. Conf. on OOPSLA}, Portland, Oregon, October
  1986.

\bibitem[Mac86]{MacQ86}
D.B. MacQueen.
\newblock Using dependent types to express modular structure.
\newblock In {\em Conf. Record 13th Ann. Symp. Principles of Programming
  Languages}, pages 277--26. ACM, January 1986.

\bibitem[Mac88]{MacQ88}
D.~MacQueen.
\newblock References and weak polymorphism.
\newblock Note in Standard ML of New Jersey Distribution Package, 1988.

\bibitem[MBCD89]{NapierRep}
R.~Morrison, A.L. Brown, R.~Connor, and A.~Dearle.
\newblock The {Napier88} reference manual.
\newblock PPRR 77-89, Universities of Glasgow and St Andrews, 1989.

\bibitem[MH88]{MiHa88}
J.C. Mitchell and R.~Harper.
\newblock The essence of {ML}.
\newblock In {\em Proc. 15th ACM Symposium on Principles of Programming
  Languages}, pages 28--46, San Diego, Ca., January 1988.

\bibitem[Mil78]{Miln78}
R.~Milner.
\newblock A theory of type polymorphism in programming.
\newblock {\em Journal of Computer and System Sciences}, 17:348--375, 1978.

\bibitem[Mos89]{Moss89}
J.E.B. Moss.
\newblock Addressing large distributed collections of persistent objects: The
  {Mneme} project's approach.
\newblock In {\em Proc. of the 2nd Workshop on Database Programming Languages,
  Portland, Oregon}, pages 358--374, June 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[OB88]{OhBu88}
A.~Ohori and P.~Buneman.
\newblock Type inference in a database programming language.
\newblock In {\em ACM Conference on Lisp and Functional Programming}, pages
  174--183, Snowbird, Utah, 1988.

\bibitem[OBBT89]{OBBT89}
A.~Ohori, P.~Buneman, and V.~Breazu-Tannen.
\newblock Database programming in {Machiavelli} -- a polymorphic language with
  static type inference.
\newblock In {\em ACM-SIGMOD International Conference on Management of Data},
  pages 46--57, Portland, Oregon, 1989.

\bibitem[Oho90]{Ohor90}
A.~Ohori.
\newblock Representing object identity in a pure functional language.
\newblock In {\em Proc. 3rd Int. Conf. on Database Theory}, Paris, France,
  1990.

\bibitem[OMS90]{OMS90}
A.~Ohori, F.~Matthes, and J.W. Schmidt.
\newblock A static type system for object locality control.
\newblock (In preparation), 1990.

\bibitem[R\'89]{remy89}
D.~R\'{e}my.
\newblock Typechecking records and variants in a natural extension of {ML}.
\newblock In D.~MacQueen, editor, {\em ACM Conf. on Principles of Programming
  Languages}, 1989.

\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[Tof88]{Toft88}
M.~Tofte.
\newblock {\em Operational Semantics and Polymorphic Type Inference}.
\newblock PhD thesis, Department of Computer Science, University of Edinburgh,
  1988.

\bibitem[Wan84]{Wand84}
M.~Wand.
\newblock A types-as-sets semantics for {Milner}-style polymorphism.
\newblock In {\em Proc. 11th ACM Symp. on Principles of Programming Languages},
  pages 158--164, January 1984.

\end{thebibliography}