Oscillation and global attractivity in a nonlinear delay difference equation Deng Hua Cheng, Ju Rang Yan (2000) Mathematica Slovaca
Oscillation criteria for second-order delay, difference, and functional equations. Kikina, L.K., Stavroulakis, I.P. (2010) International Journal of Differential Equations
Oscillation of linear functional equations of higher order W. Nowakowska, Jarosław Werbowski (1995) Archivum Mathematicum The paper contains sufficient conditions under which all solutions of linear functional equations of the higher order are oscillatory.