Koklu, Kevser, Inci Albayrak, and Azad Bayramov. “A Regularized Trace Formula for Second Order Differential Operator Equations”. Mathematica Scandinavica 107, no. 1 (September 1, 2010): 123–138. Accessed July 24, 2026. https://journals.msp.org/mscand/article/view/551.