When using OGDF in your research, please cite:
M. Chimani, C. Gutwenger, M. Jünger, G. W. Klau, K. Klein, P. Mutzel.
The Open Graph Drawing Framework (OGDF).
Chapter 17 in: R. Tamassia (ed.), Handbook of Graph Drawing and Visualization, CRC Press, 2014.
OGDF is open-source and licensed under GNU GPL. See the license page for details.