A necessary and sufficient condition for the existence of positive solutions of singular boundary value problems. - Yumei Xu; Lishan Li; Lokenath Debnath (Appl. Math. Lett., 2005)

Multiple positive solutions of a boundary value problem for a class of 2nth-order m-point singular integro-differential equations in Banach spaces. - Yumei Xu; Haijun Zhang (Appl. Math. Comput., 2009)

Positive solutions of an infinite boundary value problem for nth-order nonlinear impulsive singular integro-differential equations in Banach spaces. - Yumei Xu; Haijun Zhang (Appl. Math. Comput., 2012)