ScienceScope SCIENCESCOPE Science 18 Mar 1994:Vol. 263, Issue 5153, pp. 1551DOI: 10.1126/science.263.5153.1551 Article Info & Metrics eLetters PDF This is a PDF-only article. The first page of the PDF of this article appears above.
Science Vol 263, Issue 515318 March 1994 Table of Contents Print Table of Contents Back Matter (PDF) Ed Board (PDF) Front Matter (PDF)