Murphy, J., and R. Nichols. “Weak and Vague Convergence of Spectral Shift Functions of One-Dimensional Schrödinger Operators With Coupled Boundary Conditions”. Methods of Functional Analysis and Topology, vol. 23, no. 4, Dec. 2017, pp. 378-03, https://zen.imath.kiev.ua/index.php/mfat/article/view/678.