(a) Meetings of the board, annual, regular or special, may be held at any place within or without this state, unless otherwise provided by the certificate of incorporation or the by-laws.

(b) The time and place for holding annual or regular meetings of the board shall be fixed by or under the by-laws, or, if not so fixed, by the board.

(c) A special meeting may be called at any time by the president or other corporate officer as provided in the by-laws or as determined by the board; and, in the case of a corporation without members, by any director upon written demand of not less than one-fifth of the entire board.