Add citation tag and initial description of the splits

README.md

@@ -13,6 +13,19 @@ pretty_name: Blood-Brain Barrier Database (B3DB)
 dataset_summary: >-
   Curation of 50 published resources of categorical and numeric measurements of
   Blood-Brain Barrier penetration.
+citation: >-
+  @article{
+    Meng_A_curated_diverse_2021,
+    author = {Meng, Fanwang and Xi, Yang and Huang, Jinfeng and Ayers, Paul W.},
+    doi = {10.1038/s41597-021-01069-5},
+    journal = {Scientific Data},
+    number = {289},
+    title = {A curated diverse molecular database of blood-brain barrier permeability with chemical descriptors},
+    volume = {8},
+    year = {2021},
+    url = {https://www.nature.com/articles/s41597-021-01069-5},
+    publisher = {Springer Nature}
+  }
 size_categories:
 - 1K<n<10K
 config_names:
@@ -80,6 +93,12 @@ A subset of the molecules in B3DB has numerical `logBB` values (1058 compounds),
 while the whole dataset has categorical (`BBB+` or `BBB-`) BBB permeability labels
 (7807 compounds). Some physicochemical properties of the molecules are also provided.
 
+## Data splits
+The original B3DB dataset does not define splits, so here we have used the `Realistic Split` method described
+in [(Martin et al., 2018)](https://doi.org/10.1021/acs.jcim.7b00166).
+
+
+
 ## Citation
 Please use the following citation in any publication using our *B3DB* dataset: