1]ATKINSON F V, LANGER H,MENNLCKEN R,et al.The essential spectrum of some matrix operator[J].Math Nachr, 1994, 167(1):5-20.
[2]LAURSEN K B,NEUMANN M M.An introduction to local spectral theory[M].Oxford:Clarendon Press, 2000.
[3]LANGER H,TRETTER C.Spectral decomposition of some nonselfadjoint block operator matrices[J].J Operator Theory,1998,39:339-359.
[4]LANGER H,MARKUS A,MATSAEV V,et al.A new concept for block operator matrices: the quadratic numerical range[J].Linear algebra and its applications, 2001, 330(1-3):89-112.
[5]TRETTER C,WAGENHOFER M.The block numerical range of an block operator matrix[J].SIAM J Matrix Anal Appl, 2003, 24(4):1003-1017.
[6]TRETTER C.Spectral theory of block operator matrices and applications[M].London : Imperial College Press, 2008.
[7]SALEMI A,AFSHIN H R.Quadratic numerical range of block operator matrices[J].Far East J Math Sci,2003,10(1):99-103. [JP]〖ZK)〗〖HT〗〖HJ〗〖WT〗