Slavik V. Jablan1, Ljiljana M. Radovic2, Radmila Sazdanovic3
1The Mathematical Institute, Knez Mihailova 35, P.O. Box
367,
11001 Belgrade, Serbia and Montenegro
(e-mail:
jablans@mi.sanu.ac.yu)
2University of Nis, Faculty of
Mechanical Engineering, Beogradska 14,
Nis, Serbia and
Montenegro
(e-mail: liki@masfak.ni.ac.yu)
3The Mathematical Institute,
Knez Mihailova 35, P.O. Box 367,
11001 Belgrade, Serbia and
Montenegro
(e-mail: radmilas@gmail.com)