E. Karadzhov, Georgi. “Uniform Asymptotics of the Spectral Function for Perturbed Harmonic Oscillator and Equiconvergence of Series With Respect to the Eigenfunctions”. Ann. Sofia Univ. Fac. Math. and Inf. 83, no. 1 (December 12, 1992): 51–65. Accessed November 24, 2024. https://ftl5.uni-sofia.bg./index.php/fmi/article/view/485.