Silvija Galić, Dubravka Špiranović-Kanižaj, and Alfonzo Baumgartner. 2012. “Determination of Damage in Transparent Optically Active Materials by Using Polarized Light and the Sobel Operator”. International Journal of Electrical and Computer Engineering Systems 3 (1):41-46. https://ijeces.ferit.hr/index.php/ijeces/article/view/881.