Four different unknown functions satisfying the triangle mean value property for harmonic polynomials, II
Tom 44 / 1984
                    
                    
                        Annales Polonici Mathematici 44 (1984), 239-243                    
                                        
                        DOI: 10.4064/ap-44-3-239-243                    
                                    
                                                                
                             
             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                         
                                                            