On measurable relation
Tom 111 / 1981
                    
                    
                        Fundamenta Mathematicae 111 (1981), 161-167                    
                                        
                        DOI: 10.4064/fm-111-2-161-167                    
                                    
                                                                
                             
             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                         
                                                            