I.K. Bonset (pseudonym of Theo van Doesburg). <i>X-Beelden.</i> 1920. From <i>Het Vaderland</i>, 4 August 1920, Avondblad, p. B4.
<a href="//commons.wikimedia.org/wiki/Theo_van_Doesburg" title="Theo van Doesburg">Theo van Doesburg</a> &amp; anonymous
1920
<a rel="nofollow" class="external free" href="http://www.delpher.nl/kranten">http://www.delpher.nl/kranten</a> (newspapercollection Royal Library, The Hague)