Demir, Halit, Brahim Hakki Yoruk, Ali Savran, and Kamil Ekici. 2010. “Purificiation and Some Properties of Polyphenol Oxidase from Van Apple (Golden Delicious)”. Asian Journal of Chemistry 18 (1):475-80. https://asianpubs.org/index.php/ajchem/article/view/21354.