Skeletal formula of the santonin molecule, C<sub>15</sub>H<sub>18</sub>O<sub>3</sub>.
<a href="//commons.wikimedia.org/w/index.php?title=User:Ktns&amp;action=edit&amp;redlink=1" class="new" title="User:Ktns (page does not exist)">Ktns</a>
2017-06-25
<span class="int-own-work" lang="en">Own work</span>