@InProceedings{TALN-2008-BL-TERMGRAPH2,
 author       = {Denis B\'echet and Sylvain Lippi},
 title        = {Universal Boolean Systems},
 pages        = {19--30},
 booktitle    = {Proceedings of the Fourth International Workshop on
                 Computing with terms and graphs,
                 TERMGRAPH 2007, Braga, Portugal, 31 March 2007},
 editor       = {Ian Mackie and Detlef Plump},
 series       = {Electronic Notes in Theoretical Computer Science (ENTCS)},
 volume       = {203, Issue 1},
 publisher    = {Elsevier},
 year         = 2008,
 ISSN         = {1571-0661},
 DOI          = {10.1016/j.entcs.2008.03.031},
 URL          = {http://www.ianmackie.com/TERMGRAPH/2007/}
}