@ARTICLE{DasMarPau_j1998, author = {J{\"u}rgen~Dassow and Solomon~Marcus and Gheorghe~P\u{a}un}, title = {Convex and anti-convex languages}, journal = ijcm, year = 1998, volume = 69, pages = {1--16}, url = {http://dx.doi.org/10.1080/00207169808804705} }