@article{DBLP:journals/tc/AhnS93,
author = {Keumog Ahn and
Sartaj Sahni},
title = {NP-Hard Module Rotation Problems},
journal = {IEEE Trans. Computers},
volume = {42},
number = {12},
year = {1993},
pages = {1506-1510},
ee = {http://doi.ieeecomputersociety.org/10.1109/12.260642},
bibsource = {DBLP, http://dblp.uni-trier.de}
}