<span class="citations"><p>Hubertus L. Regtop, John R. Biffin, "Preparation of divalent metal salts of indomethacin." U.S. Patent US5310936, issued November, 1917.</p>
</span><a href="https://www.google.com/?tbm=pts#q=5310936&amp;tbm=pts" rel="noopener" target="_blank">US5310936</a>