1. Dwork, C. et al.,“On the Sequential Nature of Unification,ℍ J. Logic Programming, vol. 1(1), pp. 35–50, June 1984.
2. Yasuura, H.,“On Parallel Computational Complexity of Unification,ℍ Proc. of the Int. Conf. on Fifth Generation Computer Systems,ℍ Tokyo, Japan, pp. 235–248, Nov. 1984.
3. Citrin, W.,“Parallel Unification Scheduling in Prolog,ℍ Ph.D. Dissertation, EECS Dept., University of California, Berkeley, 1988.
4. Robinson, J.A.,“A Machine-Oriented Logic Based on the Resolution Principle,ℍ J. of the ACM, vol. 12 (1), pp. 23–41, Jan. 1965.
5. Knight, K.,“Unification:A Multidisciplinary Survey,ℍ ACM Computing Surveys, vol. 21 (1), pp. 93–124, March 1989.