Convertor for Bessemer and Thomas process, as pictured in Otto's Encyclopedia (Ottův slovník naučný, 1908)
Unknown author<span style="display: none;">Unknown author</span>. The author of the image is not given in the book, although it might be the author of the text entry <a href="https://cs.wikipedia.org/wiki/s:Autor:Josef_Pokorn%C3%BD_(technik)" class="extiw" title="cs:s:Autor:Josef Pokorný (technik)">Josef Pokorný</a>.
"Železářství." Ottův Slovník Naučný. Vol. 27. Praha: J. Otto, 1908. 775–787. Print