Distinct subjects for predicate ns4:boordgeschut sorted by frequency

Resource	Count
Consolidated PBY Catalina	2
Junkers Ju 87	2
Supermarine Spitfire	2
B-17 Flying Fortress	1
B-24 Liberator	1
Curtiss-Wright Model 21	1
Hawker Typhoon	1
Heinkel He 111	1
Messerschmitt Bf 109	1
Mitsubishi A6M Zero	1