diff --git a/grawlix/sources/nextory.py b/grawlix/sources/nextory.py
index b68761d..4c88f28 100644
--- a/grawlix/sources/nextory.py
+++ b/grawlix/sources/nextory.py
@@ -30,7 +30,7 @@ class Nextory(Source):
         self._client.headers.update(
             {
                 "X-Application-Id": "200",
-                "X-App-Version": "5.4.1",
+                "X-App-Version": "2026.05.4",
                 "X-Locale": LOCALE,
                 "X-Model": "Personal Computer",
                 "X-Device-Id": device_id,
@@ -139,9 +139,10 @@ class Nextory(Source):
 
     @staticmethod
     def _extract_series_name(product_info: dict) -> Optional[str]:
-        if not "series" in product_info:
+        series = product_info.get("series")
+        if not series:
             return None
-        return product_info["series"]["name"]
+        return series["name"]
 
 
     async def _get_book_id_from_url_id(self, url_id: str) -> str:
diff --git a/grawlix/sources/saxo.py b/grawlix/sources/saxo.py
index 77731ae..0d59b95 100644
--- a/grawlix/sources/saxo.py
+++ b/grawlix/sources/saxo.py
@@ -122,7 +122,7 @@ class Saxo(Source):
         :param url: Url of book
         :returns: Isbn of book
         """
-        isbn_match = re.search(f"\d+$", url)
+        isbn_match = re.search(r"\d+$", url)
         if isbn_match and isbn_match.group():
             return isbn_match.group()
         raise NotImplemented
diff --git a/pyproject.toml b/pyproject.toml
index 83ffec8..ebf2958 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -21,6 +21,7 @@ dependencies = [
     "pycryptodome",
     "rich",
     "tomli",
+    "urllib3",
 ]
 dynamic = ["version"]