00306nam a2200121Ia 4500082001900000100001700019245007300036260000900109300001600118490001500134490003000149500000500179  a330.183 N147b  aNagar, A. I.  aNote on the residual variance estimation in simultaneous equationsb  c1961  app. 238-243  vApril 1961  aEconometrica, v.29, no.2   a