diff --git a/citation.cff b/citation.cff
new file mode 100644
index 00000000..cfd9fd15
--- /dev/null
+++ b/citation.cff
@@ -0,0 +1,22 @@
+cff-version: 1.0.0
+message: "If you use this software, please cite it as below."
+authors:
+  - family-names: Clark
+    given-names: Andrew
+  - family-names: Foster
+    given-names: Michael
+    orcid: https://orcid.org/0000-0001-8233-9873
+  - family-names: Somers
+    given-names: Richard
+    orcid: https://orcid.org/0000-0002-1101-9722
+  - family-names: Turner
+    given-names: Robert
+    orcid: https://orcid.org/0000-0002-1353-1404
+  - family-names: Walkinshaw
+    given-names: Neil
+  - family-names: Wild
+    given-names: Christopher
+title: "Causal Testing Framework"
+version: 3.1.0
+doi: https://doi.org/10.48550/arXiv.2209.00357
+date-released: 2023-03-30
diff --git a/tests/specification_tests/test_metamorphic_relations.py b/tests/specification_tests/test_metamorphic_relations.py
index 0bd836ac..951ac729 100644
--- a/tests/specification_tests/test_metamorphic_relations.py
+++ b/tests/specification_tests/test_metamorphic_relations.py
@@ -106,9 +106,9 @@ def test_should_cause_metamorphic_relations_correct_spec_one_input(self):
         self.data_collector = SingleInputProgramUnderTestEDC(
             self.scenario, self.default_control_input_config, self.default_treatment_input_config
         )
-        causal_dag.graph.remove_nodes_from(['X2', 'X3'])
-        adj_set = list(causal_dag.direct_effect_adjustment_sets(['X1'], ['Z'])[0])
-        should_cause_MR = ShouldCause('X1', 'Z', adj_set, causal_dag)
+        causal_dag.graph.remove_nodes_from(["X2", "X3"])
+        adj_set = list(causal_dag.direct_effect_adjustment_sets(["X1"], ["Z"])[0])
+        should_cause_MR = ShouldCause("X1", "Z", adj_set, causal_dag)
         should_cause_MR.generate_follow_up(10, -10.0, 10.0, 1)
         test_results = should_cause_MR.execute_tests(self.data_collector)
         should_cause_MR.test_oracle(test_results)
diff --git a/tests/specification_tests/test_variable.py b/tests/specification_tests/test_variable.py
index e2ece117..cc76df6a 100644
--- a/tests/specification_tests/test_variable.py
+++ b/tests/specification_tests/test_variable.py
@@ -133,7 +133,6 @@ class Var(Variable):
         var = Var("v", int)
         self.assertEqual(var.typestring(), "Var")
 
-
     def test_copy(self):
         ip = Input("ip", float, norm)
         self.assertTrue(ip.copy() is not ip)
@@ -173,7 +172,7 @@ def test_neg(self):
         self.assertEqual(str(-self.i1), "-i1")
 
     def test_pow(self):
-        self.assertEqual(str(self.i1 ** 5), "i1**5")
+        self.assertEqual(str(self.i1**5), "i1**5")
 
     def test_le(self):
         self.assertEqual(str(self.i1 <= 5), "i1 <= 5")