Lege pentru crearea regiei autonome a postelor, telegrafelor si telefoanelor / Ministerul Comunicatiilor
Traite de législation : d´exploitation postales / Paul Jaccottey
Postal Laws and Regulations of the United States of America : Revised and edited in accordance with the act of confress approved February 23, 1931 / Walter F. Brown ( Postmaster General)
Postal Law and Regulations of Japan / Ministry of posts and Telecommunications