The assault on the civil registry office at Plantage Kerklaan 36, a former concert hall directly adjacent to the main entrance of Artis zoo, took place on the night of 27 March 1943. Disguised in police uniforms, the resistance group approached the security guards and told them that they had come to search the building for explosives. The guards believed their story and let them in. Two medical students then sedated the guards by injecting them with phenobarbital, and the unconscious guards were carried inside the zoo through a back door."Aanslag bevolkingsregister", Stadsarchief, Gemeente Amsterdam (Dutch, archived)"In memoriam W. Arondéus", Martinus Nijhoff, Verzameld werk II. Kritisch en verhalend proza, 1961 (Dutch, archived)
