diff --git a/bibtexparser/middlewares/names.py b/bibtexparser/middlewares/names.py
index 7bb0bdd..d0f893d 100644
--- a/bibtexparser/middlewares/names.py
+++ b/bibtexparser/middlewares/names.py
@@ -9,6 +9,7 @@
 from typing import List
 from typing import Literal
 from typing import Tuple
+from typing import Union
 
 from bibtexparser.model import Block
 from bibtexparser.model import Entry
@@ -73,7 +74,7 @@ def metadata_key(cls) -> str:
         return "separate_coauthors"
 
     # docstr-coverage: inherited
-    def _transform_field_value(self, name) -> List[str]:
+    def _transform_field_value(self, name: str) -> List[str]:
         return split_multiple_persons_names(name)
 
 
@@ -86,7 +87,7 @@ def metadata_key(cls) -> str:
         return "merge_coauthors"
 
     # docstr-coverage: inherited
-    def _transform_field_value(self, name):
+    def _transform_field_value(self, name: Union[List[str], str]) -> str:
         if isinstance(name, list):
             return " and ".join(name)
         return name
@@ -160,7 +161,7 @@ class SplitNameParts(_NameTransformerMiddleware):
     def metadata_key(cls) -> str:
         return "split_name_parts"
 
-    def _transform_field_value(self, name) -> List[NameParts]:
+    def _transform_field_value(self, name: List[str]) -> List[NameParts]:
         if not isinstance(name, list):
             raise ValueError(
                 "Expected a list of strings, got {}. "
@@ -195,7 +196,7 @@ def __init__(
     def metadata_key(cls) -> str:
         return "merge_name_parts"
 
-    def _transform_field_value(self, name) -> List[str]:
+    def _transform_field_value(self, name: List[NameParts]) -> List[str]:
         if not (isinstance(name, list) and all(isinstance(n, NameParts) for n in name)):
             raise ValueError(f"Expected a list of NameParts, got {name}. ")
 
@@ -207,7 +208,7 @@ def _transform_field_value(self, name) -> List[str]:
             raise ValueError(f"""Expected "first" or "last" style, got {self.style}. """)
 
 
-def parse_single_name_into_parts(name, strict=True):
+def parse_single_name_into_parts(name: str, strict: bool = True) -> NameParts:
     """
     Parse a name into its constituent parts: First, von, Last, and Jr.
 
@@ -502,7 +503,7 @@ def rindex(k, x, default):
     return parts
 
 
-def split_multiple_persons_names(names):
+def split_multiple_persons_names(names: str) -> List[str]:
     """
     Splits a string of multiple names.
 
diff --git a/bibtexparser/model.py b/bibtexparser/model.py
index 1f775c3..4b13935 100644
--- a/bibtexparser/model.py
+++ b/bibtexparser/model.py
@@ -4,6 +4,7 @@
 from typing import List
 from typing import Optional
 from typing import Set
+from typing import Tuple
 
 
 class Block(abc.ABC):
@@ -67,7 +68,7 @@ def set_parser_metadata(self, key: str, value: Any):
         See attribute ``parser_metadata`` for more information."""
         self._parser_metadata[key] = value
 
-    def __eq__(self, other):
+    def __eq__(self, other: object) -> bool:
         # make sure they have the same type and same content
         return (
             isinstance(other, self.__class__)
@@ -108,10 +109,10 @@ def value(self) -> str:
     def value(self, value: str):
         self._value = value
 
-    def __str__(self):
+    def __str__(self) -> str:
         return f"String (line: {self.start_line}, key: `{self.key}`): `{self.value}`"
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return (
             f"String(key=`{self.key}`, value=`{self.value}`, "
             f"start_line={self.start_line}, raw=`{self.raw}`)"
@@ -134,10 +135,10 @@ def value(self) -> str:
     def value(self, value: str):
         self._value = value
 
-    def __str__(self):
+    def __str__(self) -> str:
         return f"Preamble (line: {self.start_line}): `{self.value}`"
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return f"Preamble(value=`{self.value}`, " f"start_line={self.start_line}, raw=`{self.raw}`)"
 
 
@@ -157,10 +158,10 @@ def comment(self) -> str:
     def comment(self, value: str):
         self._comment = value
 
-    def __str__(self):
+    def __str__(self) -> str:
         return f"ExplicitComment (line: {self.start_line}): `{self.comment}`"
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return (
             f"ExplicitComment(comment=`{self.comment}`, "
             f"start_line={self.start_line}, raw=`{self.raw}`)"
@@ -183,10 +184,10 @@ def comment(self) -> str:
     def comment(self, value: str):
         self._comment = value
 
-    def __str__(self):
+    def __str__(self) -> str:
         return f"ImplicitComment (line: {self.start_line}): `{self.comment}`"
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return (
             f"ImplicitComment(comment=`{self.comment}`, "
             f"start_line={self.start_line}, raw=`{self.raw}`)"
@@ -224,7 +225,7 @@ def start_line(self) -> int:
         """The line number of the first line of this field in the originally parsed string."""
         return self._start_line
 
-    def __eq__(self, other):
+    def __eq__(self, other: object) -> bool:
         # make sure they have the same type and same content
         return (
             isinstance(other, self.__class__)
@@ -232,10 +233,10 @@ def __eq__(self, other):
             and self.__dict__ == other.__dict__
         )
 
-    def __str__(self):
+    def __str__(self) -> str:
         return f"Field (line: {self.start_line}, key: `{self.key}`): `{self.value}`"
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return f"Field(key=`{self.key}`, value=`{self.value}`, " f"start_line={self.start_line})"
 
 
@@ -256,7 +257,7 @@ def __init__(
         self._fields = fields
 
     @property
-    def entry_type(self):
+    def entry_type(self) -> str:
         """The type of the entry, e.g. ``article`` in ``@article{Cesar2013, ...}``."""
         return self._entry_type
 
@@ -265,7 +266,7 @@ def entry_type(self, value: str):
         self._entry_type = value
 
     @property
-    def key(self):
+    def key(self) -> str:
         """The key of the entry, e.g. ``Cesar2013`` in ``@article{Cesar2013, ...}``."""
         return self._key
 
@@ -343,7 +344,7 @@ def __setitem__(self, key: str, value: Any):
         """
         self.set_field(Field(key, value))
 
-    def __delitem__(self, key):
+    def __delitem__(self, key: str) -> None:
         """Dict-mimicking index.
 
         This serves for partial v1.x backwards compatibility,
@@ -351,7 +352,7 @@ def __delitem__(self, key):
         """
         self.pop(key)
 
-    def items(self):
+    def items(self) -> List[Tuple[str, Any]]:
         """Dict-mimicking, for partial v1.x backwards compatibility.
 
         For newly written code, it's recommended to use `entry.entry_type`,
@@ -361,12 +362,12 @@ def items(self):
             ("ID", self.key),
         ] + [(f.key, f.value) for f in self.fields]
 
-    def __str__(self):
+    def __str__(self) -> str:
         lines = [f"Entry (line: {self.start_line}, type: `{self.entry_type}`, key: `{self.key}`):"]
         lines.extend([f"\t`{f.key}` = `{f.value}`" for f in self.fields])
         return "\n".join(lines)
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return (
             f"Entry(entry_type=`{self.entry_type}`, key=`{self.key}`, "
             f"fields=`{self.fields.__repr__()}`, start_line={self.start_line})"
diff --git a/bibtexparser/py.typed b/bibtexparser/py.typed
new file mode 100644
index 0000000..e69de29
diff --git a/bibtexparser/splitter.py b/bibtexparser/splitter.py
index 158924e..b272c9d 100644
--- a/bibtexparser/splitter.py
+++ b/bibtexparser/splitter.py
@@ -46,7 +46,7 @@ def __init__(self, bibstr: str):
 
         self._reset_block_status(current_char_index=0)
 
-    def _reset_block_status(self, current_char_index):
+    def _reset_block_status(self, current_char_index: int) -> None:
         self._open_brackets = 0
         self._is_quote_open = False
         self._expected_next: Optional[List[str]] = None
@@ -131,7 +131,7 @@ def _move_to_closed_bracket(self) -> int:
                 )
 
     def _move_to_comma_or_closing_curly_bracket(
-        self, currently_quote_escaped=False, num_open_curls=0
+        self, currently_quote_escaped: bool = False, num_open_curls: int = 0
     ) -> int:
         """Index of the end of the field, taking quote-escape into account."""
 
diff --git a/setup.py b/setup.py
index 86aada8..d0480ea 100644
--- a/setup.py
+++ b/setup.py
@@ -31,6 +31,7 @@ def load_readme():
     long_description=load_readme(),
     python_requires=">=3.9",
     packages=setuptools.find_packages(include=["bibtexparser", "bibtexparser.*"]),
+    package_data={"bibtexparser": ["py.typed"]},
     classifiers=[
         "Development Status :: 4 - Beta",
         "Programming Language :: Python :: 3",