First published in 1902 in 16 volumes, the set was reprinted often, though not completely revised until 1921.
In lieu of revision, between 1905 and 1921 the set was a supplemented by the Colliers's Self Indexing Annual.
[citation needed] However, this was stopped in 1921 and an "yearly revision service" began.
This was also around the time that the Encyclopedia gained the subtitle "a loose-leaf and self-revising reference work".
[1][2] The University Encyclopedia of Twentieth Century Knowledge published by Collier in 1902 in 10 volumes was evidently an abridgement or reprint of this work.