diff --git a/src/bibx/__init__.py b/src/bibx/__init__.py
index b352e88..e72f105 100644
--- a/src/bibx/__init__.py
+++ b/src/bibx/__init__.py
@@ -28,7 +28,7 @@
     "read_wos",
 ]
 
-__version__ = "0.9.0"
+__version__ = "0.9.1"
 
 
 def query_openalex(
diff --git a/src/bibx/clients/openalex.py b/src/bibx/clients/openalex.py
index 695f8b8..443673c 100644
--- a/src/bibx/clients/openalex.py
+++ b/src/bibx/clients/openalex.py
@@ -26,7 +26,7 @@ class AuthorPosition(Enum):
 class Author(BaseModel):
     """An author from the openalex API."""
 
-    id: str
+    id: str | None = None
     display_name: str
     orcid: str | None = None
 
@@ -80,7 +80,7 @@ class Work(BaseModel):
     ids: dict[str, str]
     doi: str | None = None
     title: str | None = None
-    publication_year: int
+    publication_year: int | None = None
     authorships: list[WorkAuthorship]
     cited_by_count: int
     keywords: list[WorkKeyword]