Reference:

Harri Jäppinen, Timo Honkela, Heikki Hyötyniemi, and Aarno Lehtola. Hierarchical multilevel processing model for natural language database interface. In Proceedings of CAIA'88, 4th Conference on Artificial Intelligence Applications, pages 332–337. IEEE (The Computer Society of the IEEE), 1988.

Suggested BibTeX entry:

@inproceedings{Jappinen88a,
    author = {Harri J{\"{a}}ppinen and Timo Honkela and Heikki Hy{\"{o}}tyniemi and Aarno Lehtola},
    booktitle = {Proceedings of CAIA'88, 4th Conference on Artificial Intelligence Applications},
    pages = {332-337},
    publisher = {IEEE (The Computer Society of the IEEE)},
    title = {Hierarchical Multilevel Processing Model for Natural Language Database Interface},
    year = {1988},
}