Determination of Zinc Level of Catfish (Clarias Batrachus) From Sei Sikambing Market by Visible Light Spectrophotometry. jisk [Internet]. 2021 Aug. 31 [cited 2024 Nov. 21];2(2):22-8. Available from: https://ejournal.sumateraconnect.or.id/index.php/jisk/article/view/16