1. The Design and Analysis of Computer Algorithms;Aho,1974
2. A polynomial time matching algorithm of ordered tree patterns having height-constrained variables;Aikou,2005
3. Approximate string matching with don't care characters;Akutsu;Inform. Process. Lett.,1995
4. Approximate string matching with variable length don't care characters;Akutsu;IEICE Trans. Inf. Syst.,1996
5. Unification theory;Baader,2001