diff --git a/themis.fields.egg-info/SOURCES.txt b/themis.fields.egg-info/SOURCES.txt
index 2cd92c1..86f1ac9 100644
--- a/themis.fields.egg-info/SOURCES.txt
+++ b/themis.fields.egg-info/SOURCES.txt
@@ -11,5 +11,6 @@ themis/fields/__init__.py
 themis/fields/editors.py
 themis/fields/handlers.py
 themis/fields/interfaces.py
+themis/fields/marshaler.py
 themis/fields/vocabs.py
 themis/fields/widgets.py
\ No newline at end of file
diff --git a/themis/fields/__init__.py b/themis/fields/__init__.py
index 55914ec..1d8f9e0 100644
--- a/themis/fields/__init__.py
+++ b/themis/fields/__init__.py
@@ -4,6 +4,8 @@ from zope.schema import Choice, Field, List, Date, Orderable
 from zope.schema.interfaces import IFromUnicode, IChoice
 from zope.schema.interfaces import WrongType
 
+from z3c.relationfield.schema import RelationChoice, RelationList
+
 from themis.fields.interfaces import ICommission
 from themis.fields.interfaces import ICommissions
 from themis.fields.vocabs import CommissionsSource
@@ -23,10 +25,14 @@ from themis.fields.vocabs import ContactsSource
 from themis.fields.interfaces import IDateOnly
 from themis.fields.interfaces import IRadioChoice
 from themis.fields.interfaces import ISubjects, ILegisSession, IList
+from themis.fields.interfaces import IRelatedDoc
 
 from themis.fields.vocabs import SubjectsSource
 from themis.fields.vocabs import LegislativeSessionsSource
 
+from plone.formwidget.contenttree import ObjPathSourceBinder
+from z3c.relationfield.schema import Relation
+
 
 class Commission(Field):
     implements(ICommission, IChoice)
@@ -331,3 +337,18 @@ class RadioChoice(Choice):
     implements(IRadioChoice)
 
 
+class RelatedDoc(Relation):
+    implements(IRelatedDoc)
+
+    def __init__(self, **kw):
+        super(RelatedDoc, self).__init__(**kw)
+        self.vocabulary = ObjPathSourceBinder()
+
+    source = property(lambda self: self.vocabulary)
+
+    def bind(self, object):
+        """See zope.schema._bootstrapinterfaces.IField."""
+        clone = super(RelatedDoc, self).bind(object)
+        clone.vocabulary = self.vocabulary(object)
+        return clone
+
diff --git a/themis/fields/editors.py b/themis/fields/editors.py
index e523851..d3abd8a 100644
--- a/themis/fields/editors.py
+++ b/themis/fields/editors.py
@@ -12,6 +12,7 @@ from themis.fields import Contact, Contacts
 from themis.fields import Deputy, Deputies
 from themis.fields import Ministry, Ministries
 from themis.fields import DeputyOrMinistry, DeputiesOrMinistries
+from themis.fields import RelatedDoc
 from plone.schemaeditor.fields import FieldFactory
 
 @interface.implementer(editor_ifaces.IFieldEditFormSchema)
@@ -41,3 +42,5 @@ LegisSessionFactory = FieldFactory(LegisSession, u'Legislative Session')
 DateOnlyFactory = FieldFactory(DateOnly, u'Date')
 
 RadioChoiceFactory = FieldFactory(RadioChoice, u'Choice (radio)', values=[])
+
+RelatedDocFactory = FieldFactory(RelatedDoc, u'Related Document')
diff --git a/themis/fields/editors.zcml b/themis/fields/editors.zcml
index e416035..159af36 100644
--- a/themis/fields/editors.zcml
+++ b/themis/fields/editors.zcml
@@ -72,4 +72,9 @@
         component=".editors.RadioChoiceFactory"
         />
 
+    <utility
+        name="themis.fields.RelatedDoc"
+        component=".editors.RelatedDocFactory"
+        />
+
 </configure>
diff --git a/themis/fields/handlers.py b/themis/fields/handlers.py
index 00923c5..28a1fc9 100644
--- a/themis/fields/handlers.py
+++ b/themis/fields/handlers.py
@@ -10,6 +10,7 @@ if HAVE_SUPERMODEL:
     from zope.interface import implements
     from zope.component import adapts
     from plone.supermodel.interfaces import IToUnicode
+    from plone.app.relationfield.widget import RelationChoiceHandler
 
     from themis.fields import Commission, Commissions
     from themis.fields import DateOnly
@@ -20,6 +21,7 @@ if HAVE_SUPERMODEL:
     from themis.fields import DeputyOrMinistry, DeputiesOrMinistries
     from themis.fields import Contact, Contacts
     from themis.fields import LegisSession
+    from themis.fields import RelatedDoc
 
     class CommissionHandler_(BaseHandler):
         pass
@@ -91,4 +93,9 @@ if HAVE_SUPERMODEL:
 
     RadioChoiceHandler = RadioChoiceHandler_(RadioChoice)
 
+    class RelatedDocHandler_(BaseHandler):
+        pass
+
+    RelatedDocHandler = RelatedDocHandler_(RelatedDoc)
+
 
diff --git a/themis/fields/handlers.zcml b/themis/fields/handlers.zcml
index 9eb2d57..7cef426 100644
--- a/themis/fields/handlers.zcml
+++ b/themis/fields/handlers.zcml
@@ -74,4 +74,9 @@
         name="themis.fields.RadioChoice"
         />
 
+    <utility
+        component=".handlers.RelatedDocHandler"
+        name="themis.fields.RelatedDoc"
+        />
+
 </configure>
diff --git a/themis/fields/interfaces.py b/themis/fields/interfaces.py
index 8760c69..6295f2f 100644
--- a/themis/fields/interfaces.py
+++ b/themis/fields/interfaces.py
@@ -3,6 +3,7 @@ from zope.interface import Interface
 from zope.schema.interfaces import IChoice, IField, IList, IDate
 from zope import schema
 from z3c.form.interfaces import IOrderedSelectWidget
+from z3c.relationfield.interfaces import IRelation
 
 class ICommission(IField):
     '''Field containing a unicode string without newlines that is a commission.'''
@@ -82,3 +83,13 @@ class IRadioChoice(IChoice):
         required=False,
         values=[])
 
+class IRelatedDoc(IRelation):
+    default = schema.Text(
+        title=IField['default'].title,
+        description=IField['default'].description,
+        required=False)
+
+    missing_value = schema.Text(
+        title=IField['missing_value'].title,
+        description=IField['missing_value'].description,
+        required=False)
diff --git a/themis/fields/widgets.py b/themis/fields/widgets.py
index 91ad89c..7882273 100644
--- a/themis/fields/widgets.py
+++ b/themis/fields/widgets.py
@@ -18,6 +18,7 @@ from themis.fields.interfaces import IDeputy, IDeputies
 from themis.fields.interfaces import IMinistry, IMinistries
 from themis.fields.interfaces import IDeputyOrMinistry, IDeputiesOrMinistries
 from themis.fields.interfaces import IOrderedSelectAndAddWidget
+from themis.fields.interfaces import IRelatedDoc
 
 from plone.formwidget.autocomplete.interfaces import IAutocompleteWidget
 from plone.formwidget.autocomplete.widget import AutocompleteSelectionWidget
@@ -27,6 +28,7 @@ from z3c.form.browser.orderedselect import OrderedSelectWidget
 from z3c.form.browser.checkbox import CheckBoxWidget
 from z3c.form.browser.select import SelectWidget
 from z3c.form.browser.radio import RadioWidget
+from plone.formwidget.contenttree.widget import ContentTreeWidget
 
 @adapter(ICommission, IFormLayer)
 @implementer(IFieldWidget)
@@ -181,3 +183,9 @@ class OrderedSelectAndAddWidget(OrderedSelectWidget):
             self._bound_source = source
         return self._bound_source
 
+@adapter(IRelatedDoc, IFormLayer)
+@implementer(IFieldWidget)
+def RelatedDocFieldWidget(field, request):
+    '''IFieldWidget factory for RadioChoiceWidget'''
+    return FieldWidget(field, ContentTreeWidget(request))
+
diff --git a/themis/fields/widgets.zcml b/themis/fields/widgets.zcml
index 89343f3..ffd411c 100644
--- a/themis/fields/widgets.zcml
+++ b/themis/fields/widgets.zcml
@@ -29,6 +29,7 @@
     <adapter factory=".widgets.DateOnlyFieldWidget"/>
     <adapter factory=".widgets.DateFieldWidget"/>
     <adapter factory=".widgets.RadioChoiceFieldWidget"/>
+    <adapter factory=".widgets.RelatedDocFieldWidget"/>
 
     <class class=".widgets.OrderedSelectAndAddWidget">
       <require