oksana.nikiforova@rtu.lv
putintsev.sergii@gmail.com
dace.ahilcenoka@rtu.com
© 2016 Oksana Ņikiforova, Sergii Putintsev, Dace Ahiļčenoka, published by Riga Technical UniversityThis work is licensed under the Creative Commons Attribution 4.0 License.