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"Nadruk Verboden" basically means Do Not Copy.
Images via channingposters.
In another example, the text along the top announces the screening at the Luxor Theater starting on December 16 (1938). The age-restriction stamp in the lower left corner--"TOEGANG 14 JAAR"--limits audience members under the age of fourteen.
Image via cinemasterpieces.
This next one is for the Victoria, screenings starting on Friday, April 7th, 1939.
Image via benitomovieposter.