@phdthesis{publication-3387,
	author={Richter, Mathias},
	editor={Schauer, Helmut and Cap, Clemens H.},
	faculty={Faculty of Economics, Business Administration and Information Technology},
	institution={University of Zurich},
	title={VH-Graphs - a new approach to hierarchical graphs and their application to object-oriented programming},
	year=1997,
}