1. Discrete and Continuous Boundary Problems;Atkinson,1964
2. Adiabatic quantum transport in multiply connected systems;Avron;Rev. Modern Phys.,1988
3. A Prufer transformation for matrix differential equations;Barrett;Proc. Amer. Math. Soc.,1957
4. R. Carlson, Adjoint and self-adjoint differential operators on graphs, Electron. J. Differential Equations (6) (1998) 1–10.
5. Theory of Ordinary Differential Equations;Coddington,1955