1. Faculty of Hydrotechnics University of Architecture, Civil Engineering and Geodesy Hristo Smirnenski Blvd. 1 1046 Sofia Bulgaria
2. Faculty of Forest Industry University of Forestry Kl. Ohridsky Blvd. 10 1756 Sofia Bulgaria
3. Department of Physics University of Sofia J. Bouchier Blvd. 5 1164 Sofia Bulgaria