Periodic positive solutions for adelay nonlinear differential equation with piecewise constant arguments. - Genqiang Wang; Bicheng Yang; Lokenath Debnath (Appl. Math. Lett., 2004)

Existence of maximal and minimal periodic solutions for first-order functional differential equations. - Shugui Kang; Bao Shi; Genqiang Wang (Appl. Math. Lett., 2010)