Germany 28 cm/52 (11) SK C/28 - NavWeaps
283 mm/52 SK C/28 (283 mm) - War Thunder Wiki
Germany 15 cm/55 (5.9) SK C/28 - NavWeaps
How would WW2 naval history change had Scharnhorst and Gneisenau been armed with their originally deigned main battery of six 15-inch guns? - Quora
Germany 38 cm (14.96) SK C/34 - NavWeaps
WW2 German Heavy Tank Prototypes Archives - Tank Encyclopedia
List of battleships of Germany - Wikipedia
Id. naval guns - Page 49 - Axis History Forum
WW2 German SPG Prototypes Archives - Tank Encyclopedia
Germany 28 cm/52 (11) SK C/28 - NavWeaps
28 cm SK C/34 naval gun
Germany 28 cm/52 (11) SK C/28 - NavWeaps
40.6 cm SK C/34 gun - Wikipedia