Cal. Lab. Code § 1022

If upon inspection or investigation the Labor Commissioner determines that any person is employing workers in violation of Section 1021 or 1021.5, he or she may issue a citation to the person in violation. The citation may be served personally or by registered mail in accordance with subdivision (c) of Section 11505 of the Government Code. Each citation shall be in writing and shall describe the nature of the violation, including reference to the statutory provision alleged to have been violated.