Ohio Rev. Code § 1310.09: Final written expression - parol or extrinsic evidence - UCC 2A-202.

Terms with respect to which the confirmatory memoranda of the parties agree or that otherwise are set forth in a writing intended by the parties as a final expression of their agreement with respect to the terms that are included in their agreement may not be contradicted by evidence of any prior agreement or of a contemporaneous oral agreement but may be explained or supplemented by both of the following:

(A) Course of dealing, usage of trade, or course of performance;

(B) Evidence of consistent additional terms, unless the court finds the writing to have been intended also as a complete and exclusive statement of the terms of the agreement.