--- a/src/pyams_sequence/interfaces/__init__.py	Sat Jan 27 00:41:03 2018 +0100
+++ b/src/pyams_sequence/interfaces/__init__.py	Thu Feb 08 13:28:09 2018 +0100
@@ -16,6 +16,7 @@
 # import standard library
 
 # import interfaces
+from pyams_sequence.schema import InternalReference, InternalReferencesList
 from zope.annotation.interfaces import IAttributeAnnotatable
 
 # import packages
@@ -93,3 +94,21 @@
                                description=_("Prefix used to generate hexadecimal ID, placed after utility prefix. "
                                              "Generally defined at class level..."),
                                required=False)
+
+
+class IInternalReference(Interface):
+    """Internal link interface"""
+
+    reference = InternalReference(title=_("Internal reference"),
+                                  description=_("Internal link target reference. You can search a reference using "
+                                                "'+' followed by internal number, of by entering text matching "
+                                                "content title."),
+                                  required=True)
+
+
+class IInternalReferencesList(Interface):
+    """Internal references list"""
+
+    references = InternalReferencesList(title=_("Internal references"),
+                                        description=_("List of internal references"),
+                                        required=False)
\ No newline at end of file