1. 1 University of Petrosani , Department of Mining Engineering, Surveying and Constructions , Romania
2. 2 University of Petrosani , Department of Mining Engineering, Surveying and Constructions , Romania
3. 3 University of Petrosani , Department of Mining Engineering, Surveying and Constructions , Romania
4. 4 University of Petrosani , Department of Mining Engineering, Surveying and Constructions , Romania