Nikolov, Geno, and Borislava Petrova. “On the Regularity of Certain Three-Row Almost Hermitian Incidence Matrices”. Ann. Sofia Univ. Fac. Math. and Inf. 107 (December 12, 2020): 131–137. Accessed May 6, 2024. https://stipendii.uni-sofia.bg/index.php/fmi/article/view/108.