AMVAS: there existed two modification of KV-2 tank. In different sources I have met pair of their names either KV-2 Mod. 1939, KV-2 Mod. 1940, or KV-2 Mod. 1940 and KV-2 Mod. 1941.
On my site I use KV-2 Mod. 1940 and KV-2 Mod. 1941 names of those modifications.
KV-2 Mod. 1941, Ukraine, summer, 1941 [3]
KV-2M41 [1]
KV-2 in winter colors. Kalinin Front, January 1942 [2]
KV-2 Mod. 1941 [?]
KV-2 Mod. 1941 [4]
KV-2 Mod. 1941 [?]
Literature
"Tanki mira",
Moscow, Rusich, 2001
"KV-2", Voyennyje Mashiny, No. 67, ~2006
"Tankovye Vojska RKKA vo Vtoroy Mirovoy Vojne. Serijnye Mashiny 1930-45 gg. Chast III.Tyazhelyje tanki", Tankomaster, special issue 2/2007, Moscow
"Sovetskiye Tyazhelyje Tanki 1917-1941", Moscow, Exprint, 2004