@ARTICLE{Kaczorek_Tadeusz_Checking_2012, author={Kaczorek, Tadeusz}, number={No 1}, journal={Archives of Control Sciences}, howpublished={online}, year={2012}, publisher={Committee of Automatic Control and Robotics PAS}, title={Checking of the positivity of descriptor linear systems with singular pencils}, URL={http://journals.pan.pl/Content/84226/PDF/6.pdf}, doi={10.2478/v10170-011-0013-3}, }