1. Benedik, R., Bergman, S. G. A., Helfrich, H., Nord, G., Stille, H. (1983): Cylindrical Silos for Coal Storage in Gneiss with Graphite (in Swedish). BeFo, Stockholm.
2. Bieniawski, Z. T. (1979): The Geomechanics Classification in Rock Engineering Applications. Int. Congress of Rock Mechanics, Montreux.
3. Helfrich, H. (1978): Rock Mechanical Investigation. Report to Skanska (in Swedish), Report 1978-04-29.
4. Hoek, E., Brown, E. T. (1980): Underground Excavations in Rock. Inst. Mining and Metallurgy, London.
5. Stille, H., Groth, T., Fredriksson, A. (1982): FEM Analysis of Rock Mechanical Problems with JOBFEM (in Swedish). BeFo 307, 1/82. Stockholm.