TY  - JOUR
TI  - Estimation of Regression Coefficients When Some Regressors are not Always Observed
AU  - James M. Robins
AU  - Andrea G. Rotnitzky
AU  - Lue Ping Zhao
JO  - Journal of the American Statistical Association
PY  - 1994
VL  - 89
IS  - 427
DO  - 10.1080/01621459.1994.10476818
UR  - https://doi.org/10.1080/01621459.1994.10476818
ER  -