1. Comenius University, Faculty of Natural Sciences, Department of Applied and Environmental Geophysics Ilkovičova 6 Bratislava Slovakia
2. VŠB‐Technical University of Ostrava, Faculty of Mining and Geology, Institute of Geological Engineering 17 listopadu 15 708 33 Ostrava Czech Republic
3. Cumhuriyet University, Faculty of Engineering, Department of Geological Engineering 58140 Sivas Turkey
4. Yunnan Land and Resources Vocational College Kunming 652501 China