Complex sentence: It was originally published in a shorter version, named "Riders of the Dawn", in the magazine "Giant Western" in June 1951, and then published in hardback in 1956 by Bouregy and Curl and in paperback by Bantam Books in 1957.
Split into simpler sentences: It was originally published in a shorter version, named "Riders of the Dawn", in the magazine "Giant Western" in June 1951. It then was published in hardback in 1956 by Bouregy and Curl and in paperback by Bantam Books in 1957.