Update README.md

README.md

@@ -3,7 +3,7 @@ On Systematic Bias in Brain Age Estimation using Machine Learning
 
 Brain Age Prediction using Ridge Regression, Gaussian Process Regression, Support Vector Regression and Deep Neural Networks (DNNs). The DNNs are implemented with [Keras](https://keras.io/) and [TensorFlow](https://www.tensorflow.org/), as reported in the paper below, and [PyTorch](https://pytorch.org/).
 
-Hualou Liang, Fengqing Zhang and Xin Niu, [Investigating Systematic Bias in Brain Age Estimation with Application to PTSD], *Human Brain Mapping*, 2019.
+Hualou Liang, Fengqing Zhang and Xin Niu, [Investigating Systematic Bias in Brain Age Estimation with Application to PTSD]( https://doi.org/10.1002/hbm.24588), *Human Brain Mapping*, 2019.
 
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