@misc{the+poles+method+for+second+order+linear+time+varying+systems, author = {Siwczyński, Maciej i Jaraczewski, Marcin}, title = {The poles method for second-order linear time-varying systems}, journal = {Technical Transactions}, address = {Kraków}, publisher = {<a href=\"http://www.wydawnictwo.pk.edu.pl/\" target=\"_blank\">Wydawnictwo PK</a>}, date = {2015}, number = {Y. 112, iss. 4-M} }