Cal. Sts. & High. Code § 10016

Any resolution, notice, report, diagram, or assessment which is required to contain a description of the improvements, the boundaries of the assessment district or any zones therein, or the lines and dimensions of any parcel of land, may, for a full and detailed description thereof, refer to any plan or map which is on file with the clerk, the county auditor, or the county assessor and which is open to public inspection. The plan or map so referred to shall govern for all details of the description.