Štikonas, Artūras. “The Root Condition for Polynomial of the Second Degree and a Spectral Analysis for Three-Level Finite-Difference Schemes”. Lietuvos matematikos rinkinys 38, no. II (December 14, 1998): 396–401 . Accessed November 7, 2025. https://www.zurnalai.vu.lt/LMR/article/view/37944.