Bracken, Joseph A.  “Subsistent Relation: Mediating Concept for a New Synthesis?”  Journal of Religion 64 (Ap 1984): 188-204.

Abstract

The notion of subsistent relation, employed by Thomas Aquinas to explain the reality of the three divine persons within the Christian doctrine of the Trinity, likewise explains the nature of an actual entity in Whitehead's philosophy, provided that one concedes the ontological actuality of the resultant society. That is, just as three persons are nevertheless one God, so interrelated actual entities are both themselves and the new reality of a society at the same time. A new world view thus becomes possible in which the divine persons share their ongoing communitarian life with all their creatures.  [Abstract from ATLA Religion]