1. M.M.A. Andries.Graph Rewrite Systems and Visual Database Languages.PhD thesis, Leiden University, The Netherlands, 1996. Available from ftp.wi.leidenuniv.nlfile/pub/CS/PhDTheses/andries96. ps. gz.
2. M.M.A. Andries, G. Engels. A Hybrid Query Language for the Extended Entity-Relationship Model.Journal of Visual Languages and Computing7(3):321–352, 1996.
3. S.S. Chok and K. Marriott. Parsing visual languages. In18th Australasian Computer Science ConferenceGlenolg, South Australia, 1995.
4. E. Gamma, R. Helm, R. Johnson, and J. Vlissides.Design Patterns—Elements of Reusable Object-Oriented Software.Reading, Addison-Wesley, 1995.
5. E.J. Golin. Parsing visual languages with picture layout grammars.Journal of Visual Languages and Computing2(4):371–394, 1991.