Isomorphic characterizations of inner product spaces by orthogonal series with vector valued coefficients
Tom 44 / 1972
                    
                    
                        Studia Mathematica 44 (1972), 583-595                    
                                        
                        DOI: 10.4064/sm-44-6-583-595                    
                                    
                                                                
                             
             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                         
                                                            