Igavens, Andris, et al. “DIODE PUMPED YTTERBIUM FIBER LASER MARKING PROCESS PARAMETER IMPACT ON MARK QUALITY OF POLIVINILCHLORIDE (PVC) MATERIAL”. HUMAN. ENVIRONMENT. TECHNOLOGIES. Proceedings of the Students International Scientific and Practical Conference, no. 20, Apr. 2016, pp. 91-100, https://doi.org/10.17770/het2016.20.3496.