Removed second D6503-99 reference.

Author: dylanneild

v1.0.1/REFERENCE.md

@@ -547,11 +547,6 @@ Polymerase Chain Reaction (qPCR)
 with Internal Amplification Control
 (IAC) Assay</td>
   </tr>
-  <tr>
-    <td>D6503-99</td>
-    <td>Multiple tube fermentation (MPN)</td>
-    <td>ASTM D6503 - 99 (Idexx Enterolert)</td>
-  </tr>
   <tr>
     <td>biogx-ecoli</td>
     <td>qPCR</td>