diff --git a/olivertwist/rules/no_references_outside_of_its_staging_area.py b/olivertwist/rules/no_references_outside_of_its_staging_area.py
index a05fcad..b357437 100644
--- a/olivertwist/rules/no_references_outside_of_its_staging_area.py
+++ b/olivertwist/rules/no_references_outside_of_its_staging_area.py
@@ -17,16 +17,16 @@
 def no_references_outside_of_its_staging_area(
         manifest: Manifest,
 ) -> Tuple[List[Node], List[Node]]:
-    def detect_staging_references_another_staging_model_in_a_different_area(node: Node):
-        invalid_refs = [
+    def staging_depends_on_staging_in_another_area(node: Node):
+        different_staging_area_refs = [
             p
             for p in manifest.graph.predecessors(node.id)
             if manifest.get_node(p).is_staging
             if not manifest.get_node(p).area == node.area
         ]
-        return node.is_staging and len(list(invalid_refs)) > 0
+        return node.is_staging and len(list(different_staging_area_refs)) > 0
 
     passes, failures = partition(
-        detect_staging_references_another_staging_model_in_a_different_area, manifest.nodes()
+        staging_depends_on_staging_in_another_area, manifest.nodes()
     )
     return list(passes), list(failures)
diff --git a/olivertwist/rules/no_references_to_marts_from_staging.py b/olivertwist/rules/no_references_to_marts_from_staging.py
index 01618bd..151c9a7 100644
--- a/olivertwist/rules/no_references_to_marts_from_staging.py
+++ b/olivertwist/rules/no_references_to_marts_from_staging.py
@@ -17,7 +17,7 @@
 def no_references_to_marts_from_staging(
         manifest: Manifest,
 ) -> Tuple[List[Node], List[Node]]:
-    def detect_staging_depends_on_mart(node: Node):
+    def staging_depends_on_mart(node: Node):
         mart_refs = [
             p
             for p in manifest.graph.predecessors(node.id)
@@ -26,6 +26,6 @@ def detect_staging_depends_on_mart(node: Node):
         return node.is_staging and len(list(mart_refs)) > 0
 
     passes, failures = partition(
-        detect_staging_depends_on_mart, manifest.nodes()
+        staging_depends_on_mart, manifest.nodes()
     )
     return list(passes), list(failures)
diff --git a/olivertwist/rules/no_references_to_source_from_marts.py b/olivertwist/rules/no_references_to_source_from_marts.py
new file mode 100644
index 0000000..416ad90
--- /dev/null
+++ b/olivertwist/rules/no_references_to_source_from_marts.py
@@ -0,0 +1,31 @@
+# -*- coding: utf-8 -*-
+"""Staging models should have a single source.
+
+Copyright (C) 2020, Auto Trader UK
+Created 22. Dec 2020 08:40
+
+"""
+
+from typing import List, Tuple
+
+from olivertwist.manifest import Manifest, Node
+from olivertwist.ruleengine.rule import rule
+from olivertwist.rules.utils import partition
+
+
+@rule(id="no-references-to-source-from-marts", name="No references to source from marts")
+def no_references_to_source_from_marts(
+        manifest: Manifest,
+) -> Tuple[List[Node], List[Node]]:
+    def mart_depends_on_source(node: Node):
+        source_refs = [
+            p
+            for p in manifest.graph.predecessors(node.id)
+            if manifest.get_node(p).is_source
+        ]
+        return node.is_mart and len(list(source_refs)) > 0
+
+    passes, failures = partition(
+        mart_depends_on_source, manifest.nodes()
+    )
+    return list(passes), list(failures)
diff --git a/tests/rules/test_no_references_to_source_from_marts.py b/tests/rules/test_no_references_to_source_from_marts.py
new file mode 100644
index 0000000..d97ef46
--- /dev/null
+++ b/tests/rules/test_no_references_to_source_from_marts.py
@@ -0,0 +1,51 @@
+import pytest
+
+from olivertwist.manifest import Manifest
+from olivertwist.rules.no_references_to_source_from_marts import (
+    no_references_to_source_from_marts,
+)
+
+
+@pytest.fixture
+def manifest() -> Manifest:
+    return Manifest(
+        {
+            "nodes": {
+                "source_1": {
+                    "unique_id": "source_1",
+                    "resource_type": "source",
+                    "fqn": ["foo", "bar"],
+                },
+                "staging_1": {
+                    "unique_id": "staging_1",
+                    "resource_type": "model",
+                    "fqn": ["foo", "staging", "bar"],
+                },
+                "mart_1": {
+                    "unique_id": "mart_1",
+                    "resource_type": "model",
+                    "fqn": ["foo", "marts", "bar"],
+                },
+            },
+            "child_map": {
+                "source_1": ["mart_1"],
+                "staging_1": [],
+                "mart_1": [],
+            },
+            "disabled": [],
+            "sources": {
+                "source_1": {}
+            },
+        }
+
+    )
+
+
+def test_no_references_to_source_from_marts(manifest):
+    passes, failures = no_references_to_source_from_marts(manifest)
+
+    pass_ids = [p.id for p in passes]
+    failure_ids = [f.id for f in failures]
+
+    assert pass_ids == ["source_1", "staging_1"]
+    assert failure_ids == ["mart_1"]