@techreport{Schaffer2010,
author = {Schaffer, M.E. and Stillman, S.},
title= {xtoverid: Stata module to calculate tests of overidentifying restrictions after xtreg, xtivreg, xtivreg2 and xthtaylor},
year = {2010},
URL = {http://ideas.repec.org/c/boc/bocode/s456779.html},
}