Method of orthogonal projections and approximation of the spectrum of a bounded operator
Volume 65 / 1979
                    
                    
                        Studia Mathematica 65 (1979), 21-29                    
                                        
                        DOI: 10.4064/sm-65-1-21-29                    
                                    
                                                                
                             
             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                         
                                                            