Changes

Other publishers would have their versions printed within a very short time.  ''Compton's Encyclopedia'', a 26-volume work first printed in 1922, had the innovation of a "fact index" in each volume, giving bullet information on subjects not treated elsewhere in the set.  Grolier also published the ''Merit Student's Encyclopedia'' (1967) and the ''Academic American Encyclopedia'' (1980), with all three meant for junior and senior high school students.  Britannica got into the act as well, publishing ''Britannica Junior Encyclopedia'' in 1934, a work in 15 volumes written for elementary school students.

Other publishers would have their versions printed within a very short time.  ''Compton's Encyclopedia'', a 26-volume work first printed in 1922, had the innovation of a "fact index" in each volume, giving bullet information on subjects not treated elsewhere in the set.  Grolier also published the ''Merit Student's Encyclopedia'' (1967) and the ''Academic American Encyclopedia'' (1980), with all three meant for junior and senior high school students.  Britannica got into the act as well, publishing ''Britannica Junior Encyclopedia'' in 1934, a work in 15 volumes written for elementary school students.

By far the most famous of these sets, as well as the best-selling American encyclopedia of any kind, is ''World Book Encyclopedia'', first published in 1918 with 15 volumes, with an expansion to 22 volumes today.  Unlike many other encyclopedias, the World Book is published in volumes that are not uniform from the point of view of length, since each volume covers a specific letter of the alphabet.  The exceptions are C and S which, due to their length are divided into two volumes, while single volumes represent the letters J-K, N-O, Q-R, U-V, and W to Z.  ''World Book'' has a total of 14,300 pages, including about 27,500 photographs or illustrations, with many in color; over 3,800 editors helped write the articles. In the first volume (entries starting with A) the complete list of the main authors and consultants is given, with a synthetic profile and the topics they dealt with. At the end of most of the entries the name of the author is indicated.

By far the most famous of these sets, as well as the best-selling American encyclopedia of any kind, is ''World Book Encyclopedia'', first published in 1918 with 15 volumes, with an expansion to 22 volumes today.  Unlike many other encyclopedias, ''World Book'' is published in volumes that are not uniform from the point of view of length, since each volume covers a specific letter of the alphabet.  The exceptions are C and S which, due to their length are divided into two volumes, while single volumes represent the letters J-K, N-O, Q-R, U-V, and W to Z.  ''World Book'' has a total of 14,300 pages, including about 27,500 photographs or illustrations, with many in color; over 3,800 editors helped write the articles. In the first volume the complete list of the main authors and consultants is given, with a synthetic profile and the topics they dealt with. At the end of most of the entries the name of the author is indicated.

==Online encyclopedias==

==Online encyclopedias==