How can you have an ultra-secret organization without a proper logo? I mean, how would people know who you are? Obviously, HYDRA understands this on Agents of S.H.I.E.L.D. And I can tell, because I've found the HYDRA style guides.
[image src="http://thomz.com/blogall/wp-content/uploads/2014/10/hydra_styleguide.jpg" align="left" border="image_border" link="http://thomz.com/blogall/wp-content/uploads/2014/10/hydra_styleguide.pdf" alt="HAIL HYDRA!" title="" lightbox="false" ]