Authors
Ion Simaciu
Retired lecturer, Petroleum-Gas University of Ploieşti, Ploiești, Romania
Gheorghe Dumitrescu
Retired professor, High School Toma N. Socolescu, Ploiești, Romania
Viorel Drafta
Anca Baciu
Petroleum-Gas University of Ploieşti, Ploiești, Romania
Georgeta Nan
Petroleum-Gas University of Ploieşti, Ploiești, Romania