the 1997 edition has 23,000 entries with few short entries, as related subjects are usually consolidated into longer articles. a high percentage of the illustrations are in color, and more full-color illustrations had been added in recent years resulting in pictorial matter accounting for about two-fifths of the pages. bibliographies are found in the last volume which also contains the 450,000 entry essential index. an annual "collier's year book" was also published.