I would also recommend reading “The Beginning of the Road” by Marshal of the Soviet Union Vasily Chuikov. Gives very good insight into His handling of the meager resources to fight the German army in the city. This the only written account of Zaytsev’s duel with Col Konig. Side Note, Marshal Chuikov is the only MSU not buried in the Kremlin wall. He lies near his soldiers at Mamayev Kurgan in Volgograd. The main weakness in the book is that it was released in 1963 and Chuikov had to give due deference to the Communist Party in the book.
This the only written account of Zaytsevs duel with Col Konig