Skučaitė, A., Skučaitė-Bingelė, K., Pečiulytė, S., & Štikonas, A. (2010). Investigation of the spectrum for the Sturm–Liouville problem with one integral boundary condition. Nonlinear Analysis: Modelling and Control, 15(4), 501-512. https://doi.org/10.15388/NA.15.4.14321