diff --git a/doc/source/notifications.rst b/doc/source/notifications.rst
index 62f02c7d..f59e3ac7 100644
--- a/doc/source/notifications.rst
+++ b/doc/source/notifications.rst
@@ -16,12 +16,13 @@ Engines provide a way to receive notification on task and flow state
 transitions, which is useful for monitoring, logging, metrics, debugging
 and plenty of other tasks.
 
-To receive these notifications you should register a callback in
-:py:class:`~taskflow.utils.misc.Notifier` provided by engine.
-Each engine provides two of them: one notifies about flow state changes,
-and another notifies about changes of tasks.
+To receive these notifications you should register a callback with
+an instance of the the :py:class:`notifier <taskflow.utils.misc.Notifier>`
+class that is attached
+to :py:class:`engine <taskflow.engines.base.EngineBase>`
+attributes ``task_notifier`` and ``notifier``.
 
-TaskFlow also has a set of predefined :ref:`listeners <listeners>`, and
+Taskflow also comes with a set of predefined :ref:`listeners <listeners>`, and
 provides means to write your own listeners, which can be more convenient than
 using raw callbacks.
 
diff --git a/taskflow/engines/base.py b/taskflow/engines/base.py
index eb8d76ee..9255a3da 100644
--- a/taskflow/engines/base.py
+++ b/taskflow/engines/base.py
@@ -24,7 +24,13 @@ from taskflow.utils import misc
 
 @six.add_metaclass(abc.ABCMeta)
 class EngineBase(object):
-    """Base for all engines implementations."""
+    """Base for all engines implementations.
+
+    :ivar notifier: A notification object that will dispatch events that
+                    occur related to the flow the engine contains.
+    :ivar task_notifier: A notification object that will dispatch events that
+                         occur related to the tasks the engine contains.
+    """
 
     def __init__(self, flow, flow_detail, backend, conf):
         self._flow = flow