Oscillation Criteria for First Order Linear Difference Equations with Several Delay Arguments
          Koplatadze, R.; Pinelas, Sandra  
          
          Nonlinear Oscillations , 17(2) (2014), 248-267  
          http://www.imath.kiev.ua/~nosc/web/contents.php?volume=17&number=2&lang=en%20-%20number  
           
            
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