From the book reviews: "A resource for researchers and graduate students studying boundary value problems for functional differential equations. the author produces a coherent, useful and quite elegant presentation of the construction of Green's functions, accompanied by a specific set of applications related to primarily maximum and anti-maximum type principles, comparison theory and methods of upper and lower solutions. provides a readable and interesting account that will be useful to researchers who want to understand constructions of such operators." (P. W. Eloe, Mathematical Reviews, July, 2014).