drawing showing the design of a cannon by <a href="https://en.wikipedia.org/wiki/de:Albert_Benningk" class="extiw" title="w:de:Albert Benningk">w:de:Albert Benningk</a> in the Heeresgeschichtliches Museum, Vienna
unknown (K.K. Hof- und Staatsdruckerei)
1884
<a rel="nofollow" class="external free" href="https://archive.org/details/mittheilungenns10kkze">https://archive.org/details/mittheilungenns10kkze</a> after p. 32