TY - Acta mathematica scientia,Series A A1 - Rui Hua,Yaru Qi T1 - The Essential Spectrum of a Class of Anti-Triangular Operator Matrices Y1 - 2022-12-26 JF - Acta mathematica scientia, Series A JO - Acta mathematica scientia,Series A SP - 1611 EP - 1618 VL - 42 IS - 6 UR - http://121.43.60.238/sxwlxbA N1 - ER -