Complex sentence: By 1922 he overcomes the disease and in 1923 returns to Moscow where he began his serious literary activity as writer of sciencefiction novels, in 1925 his first novel Professor Dowell's head (Голова Профессора Доуэля) was published.
Split into simpler sentences: By 1922 he had overcome the disease and in 1923 returned to Moscow where he began his serious literary activity as writer of sciencefiction novels. In 1925 his first novel, "Professor Dowell's Head" (Голова Профессора Доуэля) was published.