diff --git a/lib/tc211/termbase/term.rb b/lib/tc211/termbase/term.rb
index 2e21fb4..75c8fd0 100644
--- a/lib/tc211/termbase/term.rb
+++ b/lib/tc211/termbase/term.rb
@@ -213,6 +213,11 @@ def review_indicator=(value)
       @review_indicator = value
     end
 
+    def authoritative_source=(source)
+      clean_source!(source)
+      @authoritative_source = source
+    end
+
     # authoritative-source-similarity
     #   Must be one of the following codes:
     #     identical = 1
@@ -228,6 +233,11 @@ def authoritative_source_similarity=(value)
       @authoritative_source_similarity = value
     end
 
+    def lineage_source=(source)
+      clean_source!(source)
+      @lineage_source = source
+    end
+
     # lineage-source-similarity
     #   Must be one of the following codes:
     #     identical = 1
@@ -243,6 +253,15 @@ def lineage_source_similarity=(value)
       @lineage_source_similarity = value
     end
 
+    def clean_source!(source)
+      if source.is_a?(Hash)
+        source["ref"]&.gsub!(/\(E\),?\s*/, "")
+        source["clause"]&.gsub!(/\(E\),?\s*/, "")
+      else
+        source.gsub!(/\(E\),?\s*/, "")
+      end
+    end
+
     ## value Must be one of pending tentative final
     def review_status=(value)
       unless ["", "pending", "tentative", "final"].include?(value)
diff --git a/spec/tc211/termbase/term_spec.rb b/spec/tc211/termbase/term_spec.rb
new file mode 100644
index 0000000..5723ce0
--- /dev/null
+++ b/spec/tc211/termbase/term_spec.rb
@@ -0,0 +1,28 @@
+RSpec.describe Tc211::Termbase::Term do
+  describe ".authoritative_source=" do
+    context "when contains '(E)'" do
+      let(:authoritative_source) do
+        {
+          "ref" => "ISO/TS 19159-4:2022",
+          "clause" => "(E), 3.22",
+          "link" => "http://foobar.com",
+        }
+      end
+
+      let(:expected_authoritative_source) do
+        {
+          "ref" => "ISO/TS 19159-4:2022",
+          "clause" => "3.22",
+          "link" => "http://foobar.com",
+        }
+      end
+
+      it "expect to remove '(E)' from source" do
+        expect { subject.authoritative_source = authoritative_source }
+          .to change { subject.authoritative_source }
+          .from(nil)
+          .to(expected_authoritative_source)
+      end
+    end
+  end
+end
diff --git a/spec/tc211/termbase_spec.rb b/spec/tc211/termbase_spec.rb
index e2a7bdf..0cc2814 100644
--- a/spec/tc211/termbase_spec.rb
+++ b/spec/tc211/termbase_spec.rb
@@ -116,9 +116,6 @@
                     "status" => "identical",
                   },
                 ],
-                "authoritativeSource" => [
-                  { "link" => "https://www.iso.org/standard/20057.html" },
-                ],
                 "terms" => [
                   {
                     "type" => "expression",