Schwerer Gustav, Wiki

File:Schwerer Gustav (36556135981).png - Wikipedia

Trivia: Gustav Max was based on Schwerer Gustav, the rail cannon made and used by the nazi germany, also considered the largest gun ever used in a war. : r/DuelLinks

Schwerer Gustav, VS Battles Wiki

Zarco Macross: German Railgun

Rail mounted guns

24 cm Theodor Bruno Kanone (E) - Wikipedia

What happened to the huge railway gun that Germany used in the second world war? - Quora

Could a Nazi Super Gun change the tide of war in Soviet and quickly destroy UK to avoid entry of US in WW2 which led to two front wars? - Quora

Schwerer Gustav - Hitler's giant gun - How it worked and why it turned out to be a disaster

A Shell and a Cartridge of the Schwerer Gustav Rail-Canon from WW2 in the Military Museum in Dresden. - 9GAG