Unless otherwise provided in the articles of incorporation, each stockholder shall at every meeting of the stockholders be entitled to one vote in person or by proxy for each share of the capital stock held by such stockholder, but no proxy shall be voted on after one year from its date, unless the proxy provides for a longer period, and, except where the transfer books of the corporation have been closed or a date has been fixed as a record date for the determination of its stockholders entitled to vote as provided in section 183 of this title, no share of stock shall be voted on at any election for directors which has been transferred on the books of the corporation within 20 days next preceding such election of directors.