Boltaev, Kh. Kh., and M. S. Ergashova. “The Spectrum of the Sum of Two Orthogonal Projectors in Separable Gilbert Space”. Procedia of Philosophical and Pedagogical Sciences (October 29, 2022): 26–29. Accessed November 23, 2024. https://procedia.online/index.php/philosophy/article/view/212.