1-D SCHRÖDINGER OPERATORS WITH LOCAL POINT INTERACTIONS ON A DISCRETE SET Article Kostenko Aleksey S., Malamud Mark M. Journal of Differential Equations. Academic Press Inc.. Vol. 249. 2010. P. 253-304
ON THE COMPLETENESS OF ROOT SUBSPACES OF BOUNDARY VALUE PROBLEMS FOR FIRST ORDER SYSTEMS OF ORDINARY DIFFERENTIAL EQUATIONS Article Malamud Mark M., Oridoroga Leonid L. Journal of Functional Analysis. Academic Press Inc.. Vol. 263. 2012. P. 1939-1980