"Author's copyright edition" appears in books from the late 19th-early 20th centuries, usually in foreign editions, to assure the buyer that it is an authorized printing rather than a pirated copy.
A Copyright would protect an authors idea.
A standard edition came out in 1993, and a large-print edition in 1997. Note that Scott, Foresman is the publisher; the authors are Edward L Thorndike and Clarence Lewis Barnhart.
The year of the encyclopedia is the year of the copyright; there are far too many editions to answer this question directly.
Copyright law.
An infringement of the original authors' copyright.
It depends on the edition. The 6th edition is from 2008.
The Copyright Office lists the authors, Mark Giannino and Chris Murphy, as the copyright claimants.
Each issue or edition has its own copyright information.
copyright clause
Infringement limits authors' ability to make money from their works. Part of copyright is the ability to use scarcity to create or sustain demand, but infringement eliminates scarcity.
Generally numbers (or letters) on a copyright page refer to an edition number so "12" would either mean a 12th edition or if they are 1,2 in sequence then a third edition.
it protect the rights of authors creativity