@Article{,
 author = {£. £aciński, J. Rychlewska, J. Szymczyk, C. Wo¼niak},
 title = {On a certain extention of the principle of stationary action and its applications},
 journal = {Scientific Research of the Institute of Mathematics and Computer Science},
 year = {2007},
 key = {1},
 volume = {6}
 }