Skučaitė, Agnė, and Artūras Štikonas. “Spectrum Curves for Sturm–Liouville Problem With Integral Boundary Condition”. Mathematical Modelling and Analysis 20, no. 6 (November 23, 2015): 802-818. Accessed November 25, 2024. https://jcem.vgtu.lt/index.php/MMA/article/view/1036.