Authors
Vasile Preda
”Gheorghe Mihoc-Caius Iacob” Institute of Mathematical Statistics and Applied Mathematics, ”Costin C. Kiriţescu” National Institute of Economic Research, Faculty of Mathematics and Computer Science, University of Bucharest, Bucharest
Irina Băncescu
”Costin C. Kiriţescu” National Institute of Economic Research, Bucharest, Romania
