Cal. Pub. Contract Code § 20150.8
The notices inviting formal bids shall state the time and place for the receiving and opening of sealed bids and distinctly state the project to be done. The first publication or posting of the notice shall be at least 10 days before the date of opening the bids. Notice shall be published at least twice, not less than five days apart, in a newspaper of general circulation, printed and published in the jurisdiction of the county, or, if there is no such newspaper within the jurisdiction of the county, publication shall be made in a newspaper of general circulation which is circulated in the jurisdiction of the county, or, if there is no such publication, the notice shall be posted in at least three public places within the jurisdiction of the county as have been designated by ordinance or regulation of such county as places for the posting of its notices.
In addition to notice published in a newspaper of general circulation, mailed, or posted, pursuant to this section, the county may also publish notice inviting bids in a trade publication.
Ca. Pub. Cont. Code § 20150.8