<a href="https://en.wikipedia.org/wiki/Coxeter_notation" class="extiw" title="en:Coxeter notation">en:Coxeter notation</a> for mirror removal 1+ subgroups of [4,4], similar table at <a href="//commons.wikimedia.org/w/index.php?title=Tetrakis_square_tiling&amp;action=edit&amp;redlink=1" class="new" title="Tetrakis square tiling (page does not exist)">Tetrakis_square_tiling#Symmetry</a>
Tom Ruen
<span class="int-own-work" lang="en">Own work</span>