Update README.md

Author: ccosmin97

README.md

@@ -40,7 +40,7 @@ if __name__ == "__main__":
 
 Please refer to the **Input and Output types** section for additional details on input and output data types and format.
 
- Example of the auto-contouring algorithm output on a public NSCLC-Radiomics[^2] CT case ([CT-image-only viewer link](https://viewer.imaging.datacommons.cancer.gov/v3/viewer/?StudyInstanceUIDs=1.3.6.1.4.1.32722.99.99.325293684872203513909374292566067254264&SeriesInstanceUIDs=1.3.6.1.4.1.32722.99.99.19336808942056470572520607494767608510))[^3]:
+ Example of the auto-contouring algorithm output on a public [NSCLC-Radiomics](https://doi.org/10.7937/K9/TCIA.2015.PF0M9REI) CT case ([CT-image-only viewer link](https://viewer.imaging.datacommons.cancer.gov/v3/viewer/?StudyInstanceUIDs=1.3.6.1.4.1.32722.99.99.325293684872203513909374292566067254264&SeriesInstanceUIDs=1.3.6.1.4.1.32722.99.99.19336808942056470572520607494767608510))[2]:
 ![Alt text](samples/figures/readme_figure.png)
 
 *From left to right, AI results on the CT case mentioned above: a) axial view with heart chambers highlighted, b) 3d view of heart chambers, c) 3d view of heart coronaries*. 
@@ -248,6 +248,7 @@ If you use this work in your research, please cite the following paper:
 If you have any question regarding this work, or any suggestions towards improvement, please raise an issue in github or contact us at cciausu@bwh.harvard.edu
 
 ## References
+
 [1] main paper ref
-[2] Aerts, H. J. W. L. *et al.* Data From NSCLC-Radiomics (version 4) [Data set]. The Cancer Imaging Archive. https://doi.org/10.7937/K9/TCIA.2015.PF0M9REI 
+
 [3] Fedorov A. *et al.* NCI Imaging Data Commons. Cancer Res. 81, 4188–4193 (2021).