Reference:
Computing Geometric Minimum-Dilation Graphs is NP-Hard (Panos Giannopoulos, Rolf Klein, Christian Knauer, Martin Kutz, Dániel Marx), In Int. J. Comput. Geometry Appl., volume 20, 2010.
Bibtex Entry:
@article{journals/ijcga/Computing_Geometric_Minimum-Dilation_Graphs_is_NP-Hard,
author = {Panos Giannopoulos and
Rolf Klein and
Christian Knauer and
Martin Kutz and
D{\'a}niel Marx},
title = {Computing Geometric Minimum-Dilation Graphs is NP-Hard},
journal = {Int. J. Comput. Geometry Appl.},
volume = {20},
number = {2},
year = {2010},
pages = {147-173},
doi = {10.1142/S0218195910003244},
urlx = {http://www.ai6.uni-bayreuth.de/uploads/pdf/.pdf}
}