Dunford, Nelson
Linear operators part 2: spectral theory, self adjoint operators in Hilbert space
John Wiley & Sons, 1963
 Buku Teks
Schmüdgen, Konrad
Unbounded self-adjoint operators on Hilbert space
Springer, 2012
 eBooks
Feintuch, Avraham
System theory : a Hilbert space approach
Academic Press, 1982
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Dunford, Nelson
Linear operators part III : spectral operators
John Wiley & Sons, 1971
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Dunford, Nelson
Linear operators part 1: general history
John Wiley & Sons, 1976
 Buku Teks