C. Plessl and M. Platzner, “Instance-Specific Accelerators for Minimum Covering,” Journal of Supercomputing, vol. 26, no. 2, pp. 109–129, 2003.

M. Dücker, C. Geiger, G. Lehrenfeld, W. Müller, and C. Tahedl, “A Visual Programming Language for Qualitative Data,”10.1109/VL.1997.626593__1997, doi:10.1109/VL.1997.626593 .