diff --git a/src/cpl_query/_extension/__init__.py b/src/cpl_query/_extension/__init__.py
deleted file mode 100644
index 1366227c..00000000
--- a/src/cpl_query/_extension/__init__.py
+++ /dev/null
@@ -1,25 +0,0 @@
-# -*- coding: utf-8 -*-
-
-"""
-sh_cpl-query sh-edraft Common Python library Query
-~~~~~~~~~~~~~~~~~~~
-
-sh-edraft Common Python library Python integrated Queries
-
-:copyright: (c) 2020 - 2021 sh-edraft.de
-:license: MIT, see LICENSE for more details.
-
-"""
-
-__title__ = 'cpl_query._extension'
-__author__ = 'Sven Heidemann'
-__license__ = 'MIT'
-__copyright__ = 'Copyright (c) 2020 - 2021 sh-edraft.de'
-__version__ = '2021.10.0.post1'
-
-from collections import namedtuple
-
-# imports:
-
-VersionInfo = namedtuple('VersionInfo', 'major minor micro')
-version_info = VersionInfo(major='2021', minor='10', micro='0.post1')
diff --git a/src/cpl_query/extension/__init__.py b/src/cpl_query/extension/__init__.py
index 4377947a..477e856c 100644
--- a/src/cpl_query/extension/__init__.py
+++ b/src/cpl_query/extension/__init__.py
@@ -20,6 +20,11 @@ __version__ = '2021.10.0.post1'
 from collections import namedtuple
 
 # imports:
+from iterable_abc import IterableABC
+from iterable import Iterable
+from list import List
+from ordered_iterable_abc import OrderedIterableABC
+from ordered_iterable import OrderedIterable
 
 VersionInfo = namedtuple('VersionInfo', 'major minor micro')
 version_info = VersionInfo(major='2021', minor='10', micro='0.post1')
diff --git a/src/cpl_query/_extension/iterable.py b/src/cpl_query/extension/iterable.py
similarity index 100%
rename from src/cpl_query/_extension/iterable.py
rename to src/cpl_query/extension/iterable.py
diff --git a/src/cpl_query/extension/list.py b/src/cpl_query/extension/list.py
index c642f0be..ccce5574 100644
--- a/src/cpl_query/extension/list.py
+++ b/src/cpl_query/extension/list.py
@@ -1,7 +1,9 @@
-from .._extension.iterable import Iterable
+from iterable import Iterable
 
 
 class List(Iterable):
+    r"""Implementation of :class: `cpl_query.Iterable`
+    """
 
     def __init__(self, t: type = None, values: list = None):
         Iterable.__init__(self, t, values)
diff --git a/src/cpl_query/_extension/ordered_iterable.py b/src/cpl_query/extension/ordered_iterable.py
similarity index 100%
rename from src/cpl_query/_extension/ordered_iterable.py
rename to src/cpl_query/extension/ordered_iterable.py
diff --git a/src/cpl_query/extension/ordered_iterable_abc.py b/src/cpl_query/extension/ordered_iterable_abc.py
index 7cab7e62..c0de7503 100644
--- a/src/cpl_query/extension/ordered_iterable_abc.py
+++ b/src/cpl_query/extension/ordered_iterable_abc.py
@@ -1,7 +1,7 @@
 from abc import abstractmethod
 from collections import Callable
 
-from cpl_query.extension.iterable_abc import IterableABC
+from iterable_abc import IterableABC
 
 
 class OrderedIterableABC(IterableABC):