Which covariates should be controlled in propensity score matching? Evidence from a simulation study
Statistica Neerlandica. 2012;67(2):169-180 
The role of thec-statistic in variable selection for propensity score models
Pharmacoepidemiology and Drug Safety. 2010;20(3):317-320
Variable selection for propensity score models when estimating treatment effects on multiple outcomes: a simulation study
Pharmacoepidemiology and Drug Safety. 2012;22(1):77-85
Variable selection in generalized functional linear models
Stat. 2013;2(1):86-101
Propensity Score Matching with Time-Dependent Covariates
Biometrics. 2005;61(3):721-728
Propensity Score Analysis With Fallible Covariates
Educational and Psychological Measurement. 2012;72(5):715-733
Combining Propensity Score Matching with Additional Adjustments for Prognostic Covariates
Matched Sampling for Causal Effects. 2006;282-304
Penalized Estimation Based Variable Selection for Semiparametric Regression Models with Endogenous Covariates
Advanced Materials Research. 2014;1079-1080:843-846
Balance diagnostics for comparing the distribution of baseline covariates between treatment groups in propensity-score matched samples
Statistics in Medicine. 2009;28(25):3083-3107
Comparing propensity score, propensity score with covariates and genetic algorithm methods for covariate matching in observational studies
Value in Health. 2014;17(3):A200