N.D. Cent. Code § 41-02-09: (2-202) Final expression - Parol or extrinsic evidence

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

1.By course of performance, course of dealing, or usage of trade (section 41-01-17); and

2.By evidence of consistent additional terms unless the court finds the record to have been intended also as a complete and exclusive statement of the terms of the agreement.