Products & Materials PRODUCTS and MATERIALS See allHide authors and affiliations Science 16 Apr 1982:Vol. 216, Issue 4543, pp. 326DOI: 10.1126/science.216.4543.326 Article Info & Metrics eLetters PDF This is a PDF-only article. The first page of the PDF of this article appears below.
Science Vol 216, Issue 454316 April 1982 Table of Contents Print Table of Contents Back Matter (PDF) Ed Board (PDF) Front Matter (PDF)