Bonsall, F. F. <br/><br/>
Numerical ranges of operators on normed spaces and of elements of normed algebras 
[by] F. F. Bonsall and J. Duncan. 
 - London,  Cambridge University Press,  1971. 
 - [2], ii, 142 p. 
 - London Mathematical Society. Lecture note series,  2 .
<br/><br/> Continued by the authors' Numerical ranges II. 
<br/><br/><label>ISBN: </label>0521079888 
<br/><br/><label>Universal Decimal Class. No.: </label>517.982.2  / BON