How can I read a document online? And which is better - text or PDF?

Once you find a title by searching or browsing, click on it to see the bibliographic record for the document and read an abstract. Most documents are available both in PDF format and as OCR   text files. Note, the text file contains no formatting. Tables and graphs cannot be reproduced. It is included as a "lightweight" means of examining the report. Printing and detailed reading should be performed using the PDF file. The PDF's in this site may be very large, since many are scans of the entire document. We provide an estimate of the file size for each document.