Relevant links to the argument between me, Levi Bryant, and Graham Harman:
Levi Bryant Mis-reading Whitehead?
Whitehead’s Process Atomism (Response to Graham Harman)
Object as subject-superject, or why Harman is wrong about Whitehead
Occasionalism in Whitehead and Harman
Harman’s Crucified Objects and Whitehead’s God: More on Withdrawal