diff --git a/java/src/org/apache/xml/resolver/Catalog.java b/java/src/org/apache/xml/resolver/Catalog.java
index 40b1914..a160614 100644
--- a/java/src/org/apache/xml/resolver/Catalog.java
+++ b/java/src/org/apache/xml/resolver/Catalog.java
@@ -15,6 +15,10 @@
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
+ *
+ * Portions of this code are derived from classes placed in the
+ * public domain by Arbortext on 10 Apr 2000. See:
+ * http://www.arbortext.com/customer_support/updates_and_technical_notes/catalogs/docs/README.htm
  */
 
 package org.apache.xml.resolver;