Литва
MacaitieneRenata.
Siauliai University, Siauliai, Lithuania,
Lithuania, LT-76285, Siauliai, Vilniaus St., 88
renata.macaitiene@mi.su.lt
LaurinˇcikasAntanas P.
Vilnius University Institute of Mathematics and Informatics, Vilnius, Lithuania,
Lithuania, 2600, Vilnius, Akademijos, 4
antanas.laurincikas@mif.vu.lt
