<a href="https://en.wikipedia.org/wiki/Harmonograph" class="extiw" title="w:Harmonograph">Harmonograph</a> on display at <a href="https://pt.wikipedia.org/wiki/Matemateca_IME-USP" class="extiw" title="pt:Matemateca IME-USP">Matemateca IME-USP</a> (pt)
Exhibit made by Estes Objethos Atelier photo by  <a href="//commons.wikimedia.org/wiki/User:Rodrigo.Argenton" title="User:Rodrigo.Argenton">Rodrigo Tetsuo Argenton</a>
Matemateca (IME/USP), provided via digitalization project by the user: <a href="//commons.wikimedia.org/wiki/User:Rodrigo.Argenton" title="User:Rodrigo.Argenton">Rodrigo Tetsuo Argenton</a>