Zofia Adamowicz Sergei N. Artëmov Damian Niwinski Ewa Orlowska Anna B. Romanowska Jan Wolenski 3-4 2004 126 Ann. Pure Appl. Logic 1-3 http://dx.doi.org/10.1016/j.apal.2003.10.004 db/journals/apal/apal126.html#AdamowiczANORW04