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 # CBPS: Covariate Balancing Propensity Score [![Build Status](https://travis-ci.org/kosukeimai/CBPS.svg?branch=master)](https://travis-ci.org/kosukeimai/CBPS)
 
 Implements the covariate balancing propensity score (CBPS) proposed by
-[Imai and Ratkovic (2014)]( https://doi.org/10.1111/rssb.12027). The propensity
+[Imai and Ratkovic (2014)](https://doi.org/10.1111/rssb.12027). The propensity
 score is estimated such that it maximizes the resulting covariate
 balance as well as the prediction of treatment assignment. The method,
 therefore, avoids an iteration between model fitting and balance
 checking.  The package also implements several extensions of the CBPS
 beyond the cross-sectional, binary treatment setting.  The current
 version implements the CBPS for longitudinal settings so that it can
 be used in conjunction with marginal structural models from [Imai and
-Ratkovic (2015)](DOI:10.1080/01621459.2014.956872), treatments with
+Ratkovic (2015)](https://doi.org/10.1080/01621459.2014.956872), treatments with
 three- and four-valued treatment variables, continuous-valued
 treatments from [Fong, Hazlett, and Imai (2015)]
 (http://imai.princeton.edu/research/files/CBGPS.pdf), and the