A. Igavens, J. Riekstiņš, A. Sivenkovs, Ļubomirs Lazovs, and P. Narica, “DIODE PUMPED YTTERBIUM FIBER LASER MARKING PROCESS PARAMETER IMPACT ON MARK QUALITY OF POLIVINILCHLORIDE (PVC) MATERIAL”, HET, no. 20, pp. 91–100, Apr. 2016, doi: 10.17770/het2016.20.3496.