Letters Photovoltaic Energy + See all authors and affiliations Science 05 Apr 1985:Vol. 228, Issue 4695, pp. 6DOI: 10.1126/science.228.4695.6-c J. O'M. BOCKRISFind this author on Google Scholar Find this author on PubMed Search for this author on this site Article Info & Metrics eLetters PDF This is a PDF-only article. The first page of the PDF of this article appears below.