It shall be the duty of the secretary or corresponding principal officer of each labor organization, in the case of a local labor organization, to forward a copy of each collective bargaining agreement made by such labor organization with any employer to any employee who requests such a copy and whose rights as such employee are directly affected by such agreement, and in the case of a labor organization other than a local labor organization, to forward a copy of any such agreement to each constituent unit which has members directly affected by such agreement; and such officer shall maintain at the principal office of the labor organization of which he is an officer copies of any such agreement made or received by such labor organization, which copies shall be available for inspection by any member or by any employee whose rights are affected by such agreement. The provisions of section 440 of this title shall be applicable in the enforcement of this section.