Halmos, Paul R <br/><br/>
Introduction to hilbert space and the theory of spectral multiplicity 

 - 2nd ed.  
 - New York  Dover publications  2022 
 - 114 
<br/><br/><label>ISBN: </label>9780486817330 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Spectral measures<br/>Hermitian operators