Cal. Corp. Code § 421

Each holder of shares of a close corporation, whether original or subsequent, by accepting the certificates for the shares which contain the legend required by subdivision (c) of Section 418 agrees and consents that such holder cannot make any transfer of shares which would violate the provisions of subdivision (d) of Section 418 and waives any right which such holder might otherwise have under any other law to sell such shares to a greater number of purchasers or to demand any registration thereof under the Securities Act of 1933, as now or hereafter amended, or as provided in any statute adopted in substitution therefor, or otherwise, so long as the corporation is a close corporation.