A <b>citation needed</b> icon suitable for use on signage denoting carrier's questioning of present subject matter, and the source of the knowledge that's arisen.
<div style="display:inline-block;padding:0 3px;background-color:#BDC"><a href="//commons.wikimedia.org/wiki/File:Citation-needed.svg" title="File:Citation-needed.svg"><b>Original: </b></a></div> <div style="display:inline-block;padding:3px 0;"><a href="//commons.wikimedia.org/wiki/User:Hamiltonham~commonswiki" title="User:Hamiltonham~commonswiki">Hamiltonham</a></div> <div style="display:inline-block;padding:0 3px;background-color:#CCF">Vector: </div> <div style="display:inline-block;"><a href="//commons.wikimedia.org/wiki/User:Jovianeye" title="User:Jovianeye">Jovianeye</a></div>
<a href="//commons.wikimedia.org/wiki/File:Citation-needed.svg" title="File:Citation-needed.svg">File:Citation-needed.svg</a>: <a href="//commons.wikimedia.org/wiki/File:Citation-needed.svg" class="image"><img alt="Citation-needed.svg" src="https://upload.wikimedia.org/wikipedia/commons/thumb/f/f2/Citation-needed.svg/144px-Citation-needed.svg.png" decoding="async" width="144" height="16" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/f/f2/Citation-needed.svg/216px-Citation-needed.svg.png 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/f/f2/Citation-needed.svg/288px-Citation-needed.svg.png 2x" data-file-width="512" data-file-height="58"></a> <i>by</i> <a href="//commons.wikimedia.org/wiki/User:Hamiltonham~commonswiki" title="User:Hamiltonham~commonswiki">Hamiltonham</a>