Products & Materials PRODUCTS and MATERIALS See allHide authors and affiliations Science 11 Mar 1983:Vol. 219, Issue 4589, pp. 1242-1244DOI: 10.1126/science.219.4589.1242 Article Info & Metrics eLetters PDF This is a PDF-only article. The first page of the PDF of this article appears below.
Science Vol 219, Issue 458911 March 1983 Table of Contents Print Table of Contents Ed Board (PDF) Front Matter (PDF)