diff --git a/phylogenetic/defaults/description.md b/phylogenetic/defaults/description.md
index 837745c..19c9b4d 100644
--- a/phylogenetic/defaults/description.md
+++ b/phylogenetic/defaults/description.md
@@ -12,6 +12,10 @@ We curate sequence data and metadata from NCBI as starting point for our analyse
 - [data.nextstrain.org/files/workflows/rabies/sequences.fasta.zst](https://data.nextstrain.org/files/workflows/rabies/sequences.fasta.zst)
 - [data.nextstrain.org/files/workflows/rabies/metadata.tsv.zst](https://data.nextstrain.org/files/workflows/rabies/metadata.tsv.zst)
 
+#### Clade annotation
+
+Clades are defined based on the "major clades" in [Troupin et al. 2016](https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1006041).
+
 ---
 
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