Ύδρα

http://ellines-albanoi.blogspot.gr/2014/08/inside-hydra.html

http://www.acgart.gr/acg-collection/ARTISTS/S/SpeN/SpeN1930-68-.htm

http://ellines-albanoi.blogspot.gr/2012/06/blog-post_2964.html

http://ellines-albanoi.blogspot.gr/2010/05/blog-post_6919.html

http://ellines-albanoi.blogspot.gr/2011/05/blog-post_875.html

http://ellines-albanoi.blogspot.gr/2009/05/19-2006-rnd-math.html

http://www.poros.gr/poros50/epikismos.php

http://hydra-hydrea-hydroussa.blogspot.gr/2012/05/blog-post_28.html

http://www.patakis.gr/images/files/14633.pdf

1830

https://archive.org/stream/moderntraveller16condiala#page/138/mode/2up

https://archive.org/details/moderntraveller16condiala

https://archive.org/stream/moderntraveller16condiala#page/140/mode/2up