During the purges, textbooks were often so frequently revised that students had to do without them.

It was an old establishment, and not frequently revised.

Circulars are revised frequently to reflect the most recent information on a topic.

It has been frequently revised, with the most recent edition covering events through 2005.

The role of Lisa's love interest Colin was frequently revised.

Frequently revised, it remains a standard textbook at American schools and universities.

Frequently revised, the edited text was published as a separate volume in 1841.

It was frequently revised by Cushing and his son through 1877.

Initial government estimates of economic growth are frequently revised higher.

The Cihai remains a popular dictionary and has been frequently revised.