1. Elliptic pseudodifferential operators on a closed curve;Agranovich;Trudy Moskov. Mat. Obshch.,1984
2. Scattering problems for differential operators with constant coefficients;Birman;Funktsional. Anal. i Prilozhen.,1969
3. An Introduction to Difference Equations;Elaydi,1999
4. Smilansky's model of irreversible quantum graphs: I. The absolutely continuous spectrum;Evans;J. Phys. A Math. General,2005
5. Smilansky's model of irreversible quantum graphs: II. The point spectrum;Evans;J. Phys. A Math. General,2005