Svraka, Irnesa, Mustafa Memić, Jasmina Sulejmanović, and Tidža Muhić-Šarac. 2014. “Preconcentration of Metal Ions Using Silica Gel 60 F254”. Bulletin of Chemists and Technologists of Bosnia and Herzegovina 42 (June): 11-16. https://glashem.pmf.unsa.ba/index.php/bctbh/article/view/120.