Cal. Food & Agric. Code § 35191

Every person that manufactures or imports any oleomargarine or margarine, or any substance designed as a substitute for butter, or that resembles butter, which is not made wholly from pure milk or cream, or any product resembling a milk product, shall keep a record, which gives the quantity that is sold or purchased, the name and location of the seller and purchaser, the date, and the place to which it was shipped or delivered.