<span class="citations"><p>Jih-Hua Liu, David A. Riley, "Preparation of crystal form II of clarithromycin." U.S. Patent US5844105, issued May, 1997.</p>
</span><a href="https://www.google.com/?tbm=pts#q=5844105&amp;tbm=pts" rel="noopener" target="_blank">US5844105</a>