title: Corrections and clarifications.
abstract: In the news briefing "The world's most prolific scientists" (17 Jan., p. 283), Arnold L. Rheingold, a crystallographer at the University of Delaware, was inadvertently left off the list of the top 20 most prolific scientists. The Institute for Scientific Information has corrected its list and states that Rheingold published 391 articles and other scientific communications between 1981 and the end of 1990. He should have ranked 13th on the list.