Cal. GOV § 7526

In addition to the requirements of Section 7525, the letterhead or other prominent location on official stationery of each state agency, and county, city, including, but not limited to, a chartered city, and each school district, municipal corporation, district, political subdivision, and board, commission, and agency thereof, and every other local public agency, used in communication with the public shall include, in addition to the telephone number of the agency, the address and telephone number, if different from the telephone number of the agency otherwise required to appear thereon, to which inquiry regarding the subject matter of the specific communication may be made. The address and telephone number may be typed or handwritten on the letterhead or other prominent location.