§ 3683. Uniform rates for books; films; other materials
(a)
Notwithstanding any other provision of this title, the rates of postage established for mail matter enumerated in former section
4554 of this title shall be uniform for such mail of the same weight, and shall not vary with the distance transported.
(b)
The rates of postage under former section
4554
(b)(1) of this title shall not be effective except with respect to mailings which—
(2)
are sent between—
(A)
an institution, organization, or association listed in subparagraph (A) or (B) of such former section
4554
(b)(1) and any other such institution, organization, or association;
(B)
an institution, organization, or association referred to in subparagraph (A) and any individual (other than an individual having a financial interest in the sale, promotion, or distribution of the materials involved);