Doneva, N., M. Hadzi-Nikolova, and S. Mijaklovski. “ANALYSIS OF REQUIRED CONSTRUCTION TIME FOR DRIFT IN ROCK TYPE – LEAD AND ZINK ORE”. Natural Resources and Technology, Vol. 13, no. 13, Oct. 2019, pp. 5-9, https://js.ugd.edu.mk/index.php/NRT/article/view/3065.