Operators and Matrices · Volume 14, Issue 4 𝒞-symmetric second order differential operators 14-54 Pages 871-908 DOI 10.7153/oam-2020-14-54 Downloads Short PDF Full PDF PNG Authors Horst Behncke Don B. Hinton Keywords m-functions singular operators essential spectrum non-selfadjoint operators 𝒞-Symmetric operators Green's functions Subject classes 34L05 34B20 34B27 34B40 34B60