@INPROCEEDINGS{atkuehn01,
author = {Colin Atkinson and Thomas K{\"u}hne},
editor = {Martin Gogolla and Cris Kobryn},
month = oct,
year = 2001,
title = {The Essence of Multilevel Metamodeling},
booktitle = {Proceedings of the 4$^{th}$ International Conference on the
{UML} 2000, Toronto, Canada},
series = {{LNCS} 2185},
pages = {19--33},
publisher = {Springer Verlag}
}