On certain curvature conditions on Riemannian manifolds
Tom 58 / 1990
                    
                    
                        Colloquium Mathematicum 58 (1990), 259-268                    
                                        
                        DOI: 10.4064/cm-58-2-259-268                    
                                    
                                                                
                             
             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                         
                                                            