1. Operators of Riesz type;Caradus;Pac. J. Math.,1966
2. Fundamental theorems on deficiency numbers, root numbers and indices of linear operators;Gohberg;Trans. Am. Math. Soc.,1960
3. Normally solvable operators and ideals associated with them;Gohberg;Trans. Am. Math. Soc.,1967
4. On the essential spectrum;Gustafson;J. Math. Anal. Appl.,1969