Some comments on the paper by Artigue, Isambert, Perrin and Zalc
Tom 101 / 1978
                    
                    
                        Fundamenta Mathematicae 101 (1978), 227-228                    
                                        
                        DOI: 10.4064/fm-101-3-227-228                    
                                    
                                                                
                             
             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                         
                                                            