Two-Gun Sue was written by Isabel Ostrander, using the pseudonym Douglas Grant. It was first published as an Argosy magazine All-Story Weekly, beginning March 4, 1922, and shortly thereafter as a novel. Ostrander was best-known as a mystery writer, but in Two-Gun Sue showed that she understood the gun-slinging and romance of the wild west, as well. Sylvia Poindexter and her younger brother and sister seem beseiged on all sides by rustlers and con-artists. They have less than a month to find a way to pay off their father's debts or risk losing the Circle Six ranch. What they need is nothing short of a Alladin's Lamp.
Isabel Egenton Ostrander (1883-1924) was a mystery writer of the early twentieth century who used, besides her own name, the pseudonyms Robert Orr Chipperfield, David Fox, and Douglas Grant. Christopher B. Booth is sometimes (falsely) credited as a pseudonym of hers. She was born in New York City to Thomas E Ostrander and Harriet Elizabeth Bradbrook. Her Ostrander pedigree goes back to seventeenth century Kingston, New York (Wikipedia).