Added the formatted reference to the paper

README.md

@@ -9,6 +9,10 @@ Urban Analytics Lab, National University of Singapore
 If using the data, please mention the following data sources: NUS Urban Analytics Lab, HDB Singapore, OpenStreetMap contributors, and OneMap.
 If you are using it for a nice publication, please cite the following [paper](https://doi.org/10.5194/isprs-annals-vi-4-w1-2020-37-2020):
 
+Biljecki F (2020): Exploration of open data in Southeast Asia to generate 3D building models. ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences, VI-4/W1-2020: 37-44. doi:10.5194/isprs-annals-vi-4-w1-2020-37-2020
+
+BibTeX entry:
+
 ```
 @article{2020_3dgeoinfo_3d_asean,
  author = {Biljecki, F.},