Spătaru, A (1990). "Breakwaters for the Protection of Romanian Beaches". Coastal Engineering. 14 (2). Elsevier Science Publishers: 129–146. doi:10.1016/0378-3839(90)90014-N.
espacenet.com
worldwide.espacenet.com
Pierre Danel and Paul Anglès d'Auriac (1963) Improvements in or relating to artificial blocks for building structures exposed to the action of moving water [1]
japantimes.co.jp
Hesse, Stephen (2007-07-22). "TETRAPODS". The Japan Times Online. ISSN0447-5763. Retrieved 2017-08-02.