Photo of Nieuport 31 WW1 fighter front samf4u.jpg
Unknown author<span style="display: none;">Unknown author</span>
<p><b>Original publication</b>: 1919<br></p>
<b>Immediate source</b>: <a rel="nofollow" class="external free" href="http://www.airwar.ru/enc/fww1/n31.html">http://www.airwar.ru/enc/fww1/n31.html</a>