California Code, Probate Code - PROB § 21502

(a) This part does not apply to an instrument the terms of which expressly or by necessary implication make this part inapplicable.

(b) By an appropriate statement made in an instrument, the transferor may incorporate by reference any or all of the provisions of this part.  The effect of incorporating a provision of this part in an instrument is to make the incorporated provision a part of the instrument as though the language of the incorporated provision were set forth verbatim in the instrument.  Unless an instrument incorporating a provision of this part provides otherwise, the instrument automatically incorporates the provision's amendments.