Positive almost automorphic solutions for some nonlinear delay integral equations. Long, Wei, Ding, Hui-Sheng (2008) Electronic Journal of Differential Equations (EJDE) [electronic only]
Positive solutions of a renewal equation Janusz Traple (1992) Annales Polonici Mathematici An existence theorem is proved for the scalar convolution type integral equation x ( t ) = ∫ - ∞ ∞ h ( t - s ) f ( s , x ( s ) ) d s .
Positive solutions of nonlinear delay integral equations modelling epidemics and population growth. A. Cañada, A. Zertiti (1993) Extracta Mathematicae