Steffen Becker Carlos Canal Nikolay Diakov Juan Manuel Murillo Pascal Poizat Massimo Tivoli 1-3 2007 189 Electr. Notes Theor. Comput. Sci. http://dx.doi.org/10.1016/j.entcs.2007.05.044 db/journals/entcs/entcs189.html#BeckerCDMPT07