California Commercial Code
Sec. § 2202


Terms with respect to which the confirmatory memoranda of the parties agree or which are otherwise set forth in a writing 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

(a)

By course of dealing, course of performance, or usage of trade (Section 1303); and

(b)

By 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.
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Last accessed
Jun. 6, 2016