Ogorodnikova, S., and F. Sadyrbaev. “Multiple Solutions of Nonlinear Boundary Value Problems With Oscillatory Solutions”. Mathematical Modelling and Analysis 11, no. 4 (December 31, 2006): 413-426. Accessed December 2, 2024. https://mma.vgtu.lt/index.php/MMA/article/view/9650.