3 ms·Paper: http://www.ssc.wisc.edu/cde/cdewp/98-07.pdf http://www.ssc.wisc.edu/cde/cdewp/98-07.pdfby pc 19y agoPaper: http://www.ssc.wisc.edu/cde/cdewp/98-07.pdf http://www.ssc.wisc.edu/cde/cdewp/98-07.pdf