TY  - JOUR
TI  - On estimating firm-level production functions using proxy variables to control for unobservables
AU  - Jeffrey M. Wooldridge
JO  - Economics Letters
PY  - 2009
VL  - 104
IS  - 3
DO  - 10.1016/j.econlet.2009.04.026
UR  - https://doi.org/10.1016/j.econlet.2009.04.026
ER  -