here it is !
Research, Patenting, and Technological Change Samuel S. KortumEconometrica, Vol. 65, No. 6 (Nov., 1997), pp. 1389-1419 Published by: The Econometric Society
Research, Patenting, and Technological Change Samuel S. KortumEconometrica, Vol. 65, No. 6 (Nov., 1997), pp. 1389-1419 Published by: The Econometric Society