Zeqing Liu Shin Min Kang Jeong Sheok Ume Existence and iterative approximations of nonoscillatory solutions of higher order nonlinear neutral delay differential equations. 73-88 2007 193 Applied Mathematics and Computation 1 http://dx.doi.org/10.1016/j.amc.2007.03.040 db/journals/amc/amc193.html#LiuKU07