AgarwalP., GraceS. R. and O’ReganD. (2007) “Oscillation of certain fourth-order functional differential equations”, Ukrains’kyi Matematychnyi Zhurnal, 59(3), pp. 291–313. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/3308 (Accessed: 8October2024).