Reference:

J. Desel and J. Esparza. Reachability in reversible free choice systems. In G.Choffrut und M. Jantzen, editor, Proceedings of STACS '91, number 480 in Lecture Notes in Computer Science, pages 384–397, 1991.

Suggested BibTeX entry:

@inproceedings{DE91,
    author = {J. Desel and J. Esparza},
    booktitle = {Proceedings of STACS '91},
    editor = {G.Choffrut und M. Jantzen},
    number = {480},
    pages = {384-397},
    series = {{Lecture Notes in Computer Science}},
    title = {Reachability in Reversible Free Choice Systems},
    year = {1991}
}