<span class="citations"><p>Kugita, H., Inoue, H., Ikezaki, M. and Takeo, S.; U.S. Patent 3,562,257; assigned to Tanabe Seiyaku Co.,Ltd., Japan.</p>
</span><a href="https://www.google.com/?tbm=pts#q=3562257&amp;tbm=pts" rel="noopener" target="_blank">US3562257</a>