What about copyright outside of the United States? There is no "International Copyright" per se; however, the Berne Convention and the General Agreement on Tariffs and Trade treaty (GATT treaty) allow authors to enforce their copyrights in signatory countries which include most industrialized nations. Some foreign countries still require the phrase "All Rights Reserved" but it is not necessary in the US or signatories of the Berne Convention.
Circular 38a from the Library of Congress Copyright Office will provide more information on International Copyright Relations of the United States as will the International Copyright Fact Sheet and World Intellectual Property Organization Diplomatic Conference (WIPO) Geneva.
For additional help in your understanding of Copyright terms and conditions for works published and unpublished outside of the United States see the Public Domain Chart published by Cornell Copyright Information Center.