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<h2 id="references">References</h2> <ol> <li id="fn:1"><p>K. G. Beauchamp,History of telegraphy, IET, 2001 ISBN 0-85296-792-6, page 201 <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> </ol>