Lansing, John W.  "The 'Natures' of Whitehead's God."  Process Studies 3, no. 3 (Fall 1973): 143-52.

Abstract

The primordial, consequent and superjective natures of God are not distinct parts, each with its own particular functions.  This is shown by examining the functions attributed to them and seeing that the functions are not separable.  Instead, the natures may best be understood as modes of God's relation to the world: as independent, affected and affecting.  [Abstract from The Philosopher's Index]