1. Atkinson F.V.: Discrete and Continuous Boundary Value Problems. Academic Press, London (1964)
2. Atkinson F.V., Langer H., Mennicken R.: Sturm–Liouville problems with coefficients which depend analytically on the eigenvalue parameter. Acta Sci. Math. (Szeged) 57, 25–44 (1993)
3. Avron J.: Adiabatic quantum transport in multiply connected systems. Rev. Mod. Phys. 60, 873–915 (1988)
4. Azizov T.Y., Iokhvidov I.S.: Linear Operators in Spaces with an in Metric. Wiley-Interscience, London (1989)
5. Binding P.A.: On generalised and quadratic eigenvalue problems. Appl. Anal. 12, 27–45 (1981)