California Code, Code of Civil Procedure - CCP § 454

It is not necessary for a party to set forth in a pleading the items of an account therein alleged, but he must deliver to the adverse party, within ten days after a demand thereof in writing, a copy of the account, or be precluded from giving evidence thereof. The court or judge thereof may order a further account when the one delivered is too general, or is defective in any particular.

If the pleading is verified the account must be verified by the affidavit of the party to the effect that he believes it to be true; or if the facts are within the personal knowledge of the agent or attorney for the party, or the party is not within the county where the attorney has his office or from some cause unable to make the affidavit, by the affidavit of the agent or attorney.