Authors
Răzvan-Cornel Sfetcu
Faculty of Mathematics and Computer Science, University of Bucharest, Bucharest, Romania
Elena-Graţiela Robe-Voinea
Faculty of Marine Engineering, Romanian Naval Academy “Mircea cel Bătrân”, Constanţa, Romania
Florentin Şerban
Doctoral School of Mathematics, University of Bucharest, and Bucharest Academy of Economic Studies, Bucharest