Milivojević Danas, Milica, and Milena Bogdanović. “Solving the Two-Level Hierarchical Covering Location Problem With an Electromagnetism-Like Metaheuristic”. COMPUTING AND INFORMATICS, vol. 42, no. 6, Mar. 2024, pp. 1471–1490, doi:10.31577/cai_2023_6_1471.