A small bibliography
      Articles
      
         - 
            Georg Gottlob. XPath processing in a nutshell.
      SIGMOD Records,
      2003.
      
        Abstract: 
        
      This papar shows how to process XPath queries efficiently. 
      To this end, 3 algorithms are given:
      
               - join;
 
               - staircase join;
 
               - twig join.
 
            
          
      
      Books
      
         - 
            Elliotte Rusty Harold, Means. XML in a nutshell,
      2004.
      O'Reilly.
      0-596-00764-7.
      
        References: G03