Pierre Réty Claude Kirchner Hélène Kirchner Pierre Lescanne NARROWER: A New Algorithm for Unification and Its Application to Logic Programming. 141-157 1985 conf/rta/1985 RTA db/conf/rta/rta85.html#RetyKKL85 http://dx.doi.org/10.1007/3-540-15976-2_7