A fixed point approach to the stability of a quadratic quartic functional equation in Paranormed spaces
          Ravi, K. ; Rassias, J.M.; Pinelas, Sandra; Jamuna, R.  
          
          Pan-American Mathematical Journal, 24(2) (2014), 61–84  
          http://www.internationalpubls.com/Journals/index.PanAmerican.pdf  
           
            
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