Title 9, Chapter 9, Section 32
For purposes of this part, in particular, an agreement is in writing
if it is contained in a document signed by the parties or in an
exchange of letters, telex, telegrams, or other means of
telecommunication which provide a record of the agreement, or in an
exchange of statements of claim and defense in which the existence
of an agreement is alleged by one party and not denied by another.
The reference in a contract to a document containing an arbitration
clause constitutes an arbitration agreement, provided that the
contract is in writing and the reference is such as to make that
clause part of the contract.