U.S. Code / Title 39 — Postal Service / Part IV—Mail Matter / Chapter 36—Postal Rates, Classes, and ServicesTitle 39SubchapterSubchapter Vi—GeneralContents§ 3681. Reimbursement§ 3682. Size and weight limits§ 3683. Uniform rates for books; films; other materials§ 3684. Limitations§ 3685. Filing of information relating to periodical publications§ 3686. Bonus authority