Update README.md

README.md

@@ -243,8 +243,10 @@ done
 
 ## References
 For the use of this code (EnergyDensity) in your research, please consider citing following papers:
-1. Han, R.; Rodríguez-Mayorga, M.; Luber, S. A Machine Learning Approach for MP2 Correlation Energies and Its Application to Organic Compounds. J. Chem. Theory Comput. 2021, 17, 777. 
+1. Han, R.; Rodríguez-Mayorga, M.; Luber, S. A Machine Learning Approach for MP2 Correlation Energies and Its Application to Organic Compounds. J. Chem. Theory Comput. 2021, 17, 777.
+https://pubs.acs.org/doi/abs/10.1021/acs.jctc.0c00898
 2. Han, R.; Luber, S. Fast Estimation of Møller–Plesset Correlation Energies Based on Atomic Contributions. J. Phys. Chem. Lett. 2021, 12, 5324–5331.
+https://pubs.acs.org/doi/10.1021/acs.jpclett.1c00900
 
 ```bash
 @article{mp2_ed,