Zhukov's Greatest Defeat by Glanz
http://www.kansaspress.ku.edu/glazhu.html
In my opinion if you have not read this you should if you think you want to know all about Ostfront...( I am reading the last pages of the book right now)
"The twin operations Mars and Uranus formed the centerpiece of Soviet strategic efforts in the fall of 1942. Designed to dislodge the German Army from its position west of Moscow, Mars cost the Soviets an estimated 335,000 dead, missing, and wounded men and over 1,600 tanks."
BTW, at the same time as Stalingrad was besieged some 40,000 Red Army soldiers were getting surrounded in the battles of the city Belyi, but managed to escape...
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I am pretty sure this was also one of the reasons why Hitler wanted to hang onto Stalingrad. He must have believed the Red Army could not feed troops and tanks to the Southern sector after the massive losses in the Rzhev area battles and the 6th Army could be relieved quite easily at the latest in January.