Ordered and unordered tree inclusion

Reference:

P. Kilpeläinen and Heikki Mannila. Ordered and unordered tree inclusion. SIAM Journal on Computing, 24(2):340–356, 1995.

Suggested BibTeX entry:

@article{kmsicomp,
    author = {P. Kilpel{\"a}inen and Heikki Mannila},
    journal = {SIAM Journal on Computing},
    number = {2},
    pages = {340-356},
    title = {Ordered and unordered tree inclusion},
    volume = {24},
    year = {1995},
}