1    
    
                  
                                            Vydáno 1977                                  
                                              “...American Alliance for Health, Physical Education, and Recreation. Research Council....”
          Kniha
                  
              
      
      2    
    
                  
                                            Vydáno 1975                                  
                                              “...American Alliance for Health, Physical Education, and Recreation....”Available online:
          Časopis
              
      