oksana.nikiforova@rtu.lv
konstantins.gusarovs@gmail.com
olegs.gorbik@rtu.lv
natalja.pavlova@rtu.lv
© 2013 Oksana Nikiforova, Konstantins Gusarovs, Olegs Gorbiks, Natalja Pavlova, published by Riga Technical UniversityThis work is licensed under the Creative Commons License.