An extended arithmetic of ordinal numbers
Tom 65 / 1969
                    
                    
                        Fundamenta Mathematicae 65 (1969), 95-127                    
                                        
                        DOI: 10.4064/fm-65-1-95-127                    
                                    
                                                                
                             
             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                         
                                                            