diff --git a/requirements.txt b/requirements.txt
index 77e2451..47e034b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,6 +5,7 @@ fastapi==0.65.1
 gunicorn==20.1.0
 h11==0.12.0
 httptools==0.2.0
+isbnlib==3.10.8
 pydantic==1.8.2
 python-dotenv==0.17.1
 PyYAML==5.4.1