diff --git a/docs/images/external_dependency.png b/docs/images/external_dependency.png
index 317903ec..4195412e 100644
Binary files a/docs/images/external_dependency.png and b/docs/images/external_dependency.png differ
diff --git a/docs/providers/extending.rst b/docs/providers/extending.rst
new file mode 100644
index 00000000..fd272267
--- /dev/null
+++ b/docs/providers/extending.rst
@@ -0,0 +1,2 @@
+Extending of providers
+----------------------
diff --git a/docs/providers/external_dependency.rst b/docs/providers/external_dependency.rst
index ebbdd800..91fd629c 100644
--- a/docs/providers/external_dependency.rst
+++ b/docs/providers/external_dependency.rst
@@ -20,7 +20,7 @@ because they would be able to find right place / right way for doing this
 in their application's architectures.
 
 At the same time, you can be sure, that your external dependency will be
-satisfied by appropriate instance.
+satisfied with appropriate instance.
 
 
 Example:
@@ -32,8 +32,8 @@ Example:
     dependency on database connection, which can be satisfied with any
     DBAPI 2.0 database connection. Being a self-sufficient library,
     ``UserService`` doesn't hardcode any kind of database management logic.
-    Instead of this, ``UserService`` provides external dependency, that has to
-    be satisfied out of library's scope.
+    Instead of this, ``UserService`` has external dependency, that has to
+    be satisfied by cleint's code, out of library's scope.
 
 .. image:: /images/external_dependency.png
 
@@ -58,12 +58,14 @@ Example:
 
         """Example class UserService.
 
-        UserService has dependency on DBAPI 2.0 database connection."""
+        UserService has dependency on DBAPI 2.0 database connection.
+        """
 
         def __init__(self, database):
             """Initializer.
 
-            Database dependency need to be injected via init arg."""
+            Database dependency need to be injected via init arg.
+            """
             self.database = database
 
         def init_database(self):
@@ -90,14 +92,14 @@ Example:
 
 
     # Database and UserService providers:
-    database = ExternalDependency(instance_of=sqlite3.Connection)
+    database = ExternalDependency(instance_of=sqlite3.dbapi2.Connection)
     users_service_factory = Factory(UserService,
                                     KwArg('database', database))
 
     # Out of library's scope.
     #
     # Setting database provider:
-    database.provided_by(Singleton(sqlite3.Connection,
+    database.provided_by(Singleton(sqlite3.dbapi2.Connection,
                                    KwArg('database', ':memory:'),
                                    KwArg('timeout', 30),
                                    KwArg('detect_types', True),
@@ -117,4 +119,3 @@ Example:
     # Making some asserts:
     assert test_user['id'] == 1
     assert test_user['name'] == 'test_user'
-
diff --git a/docs/providers/index.rst b/docs/providers/index.rst
index 070c57c7..352d73e7 100644
--- a/docs/providers/index.rst
+++ b/docs/providers/index.rst
@@ -14,3 +14,4 @@ All providers are callable. They describe how particular objects are provided.
     callable
     external_dependency
     delegation
+    extending
diff --git a/examples/providers/external_dependency.py b/examples/providers/external_dependency.py
index c4b3ef04..796be0e3 100644
--- a/examples/providers/external_dependency.py
+++ b/examples/providers/external_dependency.py
@@ -17,12 +17,14 @@ class UserService(object):
 
     """Example class UserService.
 
-    UserService has dependency on DBAPI 2.0 database connection."""
+    UserService has dependency on DBAPI 2.0 database connection.
+    """
 
     def __init__(self, database):
         """Initializer.
 
-        Database dependency need to be injected via init arg."""
+        Database dependency need to be injected via init arg.
+        """
         self.database = database
 
     def init_database(self):
@@ -49,14 +51,14 @@ class UserService(object):
 
 
 # Database and UserService providers:
-database = ExternalDependency(instance_of=sqlite3.Connection)
+database = ExternalDependency(instance_of=sqlite3.dbapi2.Connection)
 users_service_factory = Factory(UserService,
                                 KwArg('database', database))
 
 # Out of library's scope.
 #
 # Setting database provider:
-database.provided_by(Singleton(sqlite3.Connection,
+database.provided_by(Singleton(sqlite3.dbapi2.Connection,
                                KwArg('database', ':memory:'),
                                KwArg('timeout', 30),
                                KwArg('detect_types', True),