TY  - JOUR
TI  - Instrumental Variables and the Search for Identification: From Supply and Demand to Natural Experiments
AU  - Joshua D. Angrist
AU  - Alan B Krueger
JO  - The Journal of Economic Perspectives
PY  - 2001
VL  - 15
IS  - 4
DO  - 10.1257/jep.15.4.69
UR  - https://doi.org/10.1257/jep.15.4.69
ER  -