diff --git a/pyproject.toml b/pyproject.toml
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -9,6 +9,9 @@ python = "^3.10"
 requests = "^2.27.1"
 click = "^8.0.3"
 rich = "^11.2.0"
+isbnlib = "^3.10.10"
+isbnlib-worldcat2 = "^0.1.2"
+requests-cache = "^0.9.3"
 
 [tool.poetry.dev-dependencies]
 mypy = "^0.931"