After 244 years, Encyclopædia Britannica is shelving its print edition.
Officials said the end of the printed, 32-volume set has been foreseen for some time.
"This has nothing to do with Wikipedia or Google," Britannica President Jorge Cauz said. "This has to do with the fact that now Britannica sells its digital products to a large number of people."
According to Cauz, the top year for the printed encyclopedia was 1990, when 120,000 sets were sold, with that number falling to 40,000 just six years later. The company started exploring digital publishing in the 1970s, with the first CD-ROM edition published in 1989 and an online version in 1994.
The final hardcover encyclopedia set is available for sale at Britannica's website for $1,395.
"The sales of printed encyclopedias have been negligible for several years," Cauz said. "We knew this was going to come."
The company plans to mark the end of the print version by making the contents of its website available for free for one week, starting Tuesday.
Britannica reports that online versions of the encyclopedia now serve more than 100 million people around the world. The encyclopedia has become increasingly portable with a mobile edition and social, allowing users to send comments to editors.
"A printed encyclopedia is obsolete the minute that you print it," Cauz said. "Whereas our online edition is updated continuously."
Britannica has thousands of expert contributors from around the world, including Nobel laureates and world leaders such as former President Bill Clinton and Archbishop Desmond Tutu. It also has a staff of more than 100 editors.
"To me, the most important message is that the printed edition was not what made Britannica," Cauz said. "The most important thing about Britannica is that Britannica is relevant and vibrant because it brings scholarly knowledge to an editorial process to as many knowledge seekers as possible."
The Associated Press contributed to this report.