@inproceedings{Schr91a,
author = {M.~Schrefl},
booktitle = {{The Core of Conceptual Modelling, Proc. of the 9th International Conference on Entity-Relationship Approach (ER `90), Lausanne, Switzerland, October 8--10, 1990}},
editor = {H.~Kangassalo},
pages = {113--128},
publisher = {Elsevier Science B.V. (North-Holland)},
title = {{Behavior Modeling by Stepwise Refining Behavior Diagrams}},
year = {1991}
}