@ARTICLE{Lewiński_T._A_2012,
 author={Lewiński, T. and Czarnecki, S.},
 volume={60},
 number={No 2},
 journal={Bulletin of the Polish Academy of Sciences Technical Sciences},
 pages={191-204},
 howpublished={online},
 year={2012},
 title={A stress-based formulation of the free material design problem with the trace constraint and single loading condition},
 URL={http://journals.pan.pl/Content/83522/PDF/02_paper.pdf},
 doi={10.2478/v10175-012-0026-5},
}