Given name: Unknown Family name: Klienzigow
A well-known Warsaw antiquarian - in hiding.
Most probably the author made a mistake in his surname - the well known Warsaw antiquarian's name was Kleinsinger.
Reicher, Edward W ostrym świetle dnia. Dziennik żydowskiego lekarza 1939-1945 (In Broad Daylight. A Diary of a Jewish Doctor 1939 - 1945)