This is the (European) scholar's encyclopedia for the early Church. Produced by the Institutum Patristicum Augustinianum (originally in Italian) and published in English by Oxford in 1992, it represents the work of 167 scholars from 17 countries.
Expansive work that includes the literary forms of the NT (Epistles and Gospels). At least one reviewer finds the authors' personal opinions spilling over regrettably into the articles, and the bibliographies are scant.
"The Westminster Dictionary of New Testament and Early Christian Literature and Rhetoric details the variety of literary and rhetorical forms found in the New Testament and in the literature of the early Christian church." From book jacket