7C2 [Interpretation of Convention: recourse to general principles on which Convention is based];

8C [Interpretation of party's statements or other conduct (interpretation in light of surrounding circumstances): practices established by the parties, usages];

9C [Usages and practices: practices established by the parties];

11A [Formal requirements: writing or other formality for conclusion of contract not required];

18A [Acceptance of offer (time and manor): criteria for acceptance]