TY  - BOOK
AU  - Lechner,Michael
TI  - The estimation of causal effects by difference-in-difference methods
T2  - Foundations and trends in econometrics
SN  - 9781601984982
PY  - 0000///ò011
CY  - Boston
PB  - Now
N1  - Includes bibliographical references : (pages 50-60)
ER  -