↑ Remnick, David (April 14, 2003). "Seasons in Hell". The New Yorker. สืบค้นเมื่อ March 27, 2017.
↑ Other Soviet penal-labor systems not formally included in the GULag were: (a) camps for prisoners of war captured by the Soviet Union, administered by GUPVI (b) filtration camps set up during World War II for the temporary detention of Soviet Ostarbeiters and prisoners of war while the security organs screened them in order to "filter out" the black sheep, (c) "special settlements" for internal exiles including "kulaks" and deported ethnic minorities, such as Volga Germans, Poles, Balts, Caucasians, Crimean Tartars, and others. During certain periods of Soviet history, each of these camp systems held millions of people. Many hundreds of thousands were also sentenced to forced labor without imprisonment at their normal place of work. (Applebaum, pages 579–580)
