TY  - JOUR
A1  - Heckman, J.J.
A1  - Walker, J.R.
T1  - The third birth in Sweden
Y1  - 1990b
DO  - 10.1007/BF00179336
JF  - Journal of Population Economics
VL  - 3
IS  - 4
SP  - 235
EP  - -275

ER  -