00277nam a2200121Ia 4500082001900000100001800019245005400037260000900091300000600100490001400106490003000120500000500150  a330.183 F533b  aFisher, F. M.  aIndentifiability criteria in non-linear systemsb  c1961  a   vOct. 1961  aEconometrica, v.29, no.4   a