Dunford, Nelson
Linear operators part III : spectral operators
John Wiley & Sons, 1971
 Buku Teks SO
Neerven, Jan van
The adjoint of a semigroup of linear operators
Springer-Verlag, 1992
 Buku Teks SO
Akhiezer, N.I.
Theory of linear operators in Hilbert space /N.I. Akhiezer and I.M. Glazman ; translated from the Russian by Merlynd Nestell.
Frederick Ungar Publishing Co, 1963
 Buku Teks SO
Dunford, Nelson
Linear operators part 1: general history
John Wiley & Sons, 1976
 Buku Teks SO
Schmüdgen, Konrad
Unbounded self-adjoint operators on Hilbert space
Springer, 2012
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