Both authors work in the Department of Field Theory at the Marian Smoluchowski Institute of Physics, Jagiellonian University, Cracow. They are experienced academic teachers specialized in theoretical and mathematical physics. Professor Henryk Arodz has published research papers on the Yang - Mills fields, topological defects, and several other topics in field theory and quantum mechanics. Dr. Leszek Hadasz has investigated, among other things, exactly solvable models with (super-)conformal symmetry and strings in non-critical dimensions.