@TECHREPORT{Schmidt98a,
AUTHOR = {Schmidt, R. A.},
MONTH = {April},
YEAR = {1998},
TITLE = {{$E$}-Unification for Subsystems of {S4}},
TYPE = {Research Report},
NUMBER = {MPI-I-98-2-003},
INSTITUTION = {Max-Planck-Institut f{\"u}r Informatik},
ADDRESS = {Saarbr{\"u}cken, Germany},
NOTE = {Long version of a paper published in
Nipkow, T. (eds),
\emph{Rewriting Techniques and Applications: 9th International
Conference, RTA'98, Proceedings},
Lecture Notes in Computer Science, Vol.\ 1379, Springer, 106--120.},
URL = {http://www.cs.man.ac.uk/~schmidt/publications/Schmidt98a.html},
}