California Code, Elections Code - ELEC § 13300

(a) By at least 29 days before the partisan primary, each county elections official shall prepare a separate county voter information guide for each political party and a separate nonpartisan county voter information guide. The county elections official shall place in each guide, as applicable, in the order provided in Chapter 2 (commencing with Section 13100), and under the appropriate title of each office, the names of all candidates for whom nomination papers have been duly filed with the county elections official or have been certified to the county elections official by the Secretary of State, to be voted for in the county elections official's county at the partisan primary election.

(b) The county voter information guides shall include a substantial facsimile of the official ballots, except as otherwise provided by law. The county voter information guides shall be printed on paper of a different texture from the paper to be used for the official ballot.

(c) One county voter information guide of the party for which the voter has disclosed a preference, as evidenced by the voter's registration, shall be mailed no later than 10 days before the election to each voter entitled to vote at the primary who registered at least 29 days before the election. A nonpartisan county voter information guide shall be so mailed to each voter who is not registered as preferring any of the parties participating in the primary election. On election day the voter may, upon request, vote the ballot of a political party if authorized by the party's rules, duly noticed to the Secretary of State.