Davcheva, D., G. Kirova, D. Terzieva, and K. Simitchiev , trans. “Reference Intervals of Serum Copper, Selenium, Rubidium, Zinc, and Magnesium With Evaluation of the Influence of Age, Sex, and Physical Activity”. Bulgarian Medical Journal 20, no. 2 (August 21, 2026): 67–72. Accessed August 24, 2026. https://journals.mu-sofia.bg/index.php/bmj/article/view/1112.