Dual properties within graph theory
Tom 128 / 1987
                    
                    
                        Fundamenta Mathematicae 128 (1987), 91-97                    
                                        
                        DOI: 10.4064/fm-128-2-91-97                    
                                    
                                                                
                             
             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                         
                                                            