Ernst Wiesner, who was a circuit overseer in Germany at that time, described some of the security measures: “Two brothers went ahead and whenever they met anyone, they at once signaled with their flashlights.
Ernst Wiesner, pengawas wilayah di Jerman kala itu, menjelaskan salah satu tindakan pengamanan, ” Dua saudara berjalan lebih dulu dan akan langsung memberi tanda dengan senter kalau bertemu seseorang.