1. L.Alonso, R.Schott, On the tree inclusion, preprint.
2. J.Cai, R.Paige, R.Tarjan, More efficient bottom-up tree pattern matching, Proc. CAAP'90, LNCS 431, 72–86.
3. C.M.Hoffman, M.J.O'Donnell, Pattern matching in trees, J.A.C.M., 29, 1, 68–95, 1992.
4. P.Kilpeläinen, H.Mannila, The tree inclusion problem, CAAP 91, LNCS 493, 202–214, 1991.
5. D.E.Knuth, The art of computer programming, Fundamental Algorithms, 1, Addison Wesley, 1973.