Michael J Boskin and Sheshinski, Eytan . 1978. ?Optimal Redistributive Taxation When Individual Welfare Depends Upon Relative Income.?. http://search.ebscohost.com/login.aspx?direct=true&db=edsbas&AN=edsbas.fthighwire.oai.open.archive.highwire.org.qje.92.4.589&site=eds-live.