<span class="citations"><p>Charles G. Chavdarian, Edward B. Sanders, "Process for the preparation of optically active nicotine analogs." U.S. Patent US4321387, issued September, 1959.</p>
</span><a href="https://www.google.com/?tbm=pts#q=4321387&amp;tbm=pts" rel="noopener" target="_blank">US4321387</a>