The photographers of the statistical department of the Judenrat, besides their official work, illegally took photos of everyday scenes and atrocities. One of them, Henryk Ross, managed to bury the negatives and dig them up after liberation, at 12 Jagielonska Street. Because of this archive, the reality of the ghetto was recorded and preserved. The archivists also began creating a ghetto encyclopedia and a lexicon of the local slang that emerged in their daily lives. The Jewish population maintained several illegal radios with which they kept abreast of events in the outside world. At first, the radio could only receive German broadcast, which is why it was codenamed the "Liar" in the diaries. Among the news that quickly spread around the ghetto was the Allied invasion of Normandy on the day it occurred.