What to read after Chip of the Flying U?

The weekly mail had just arrived at the Flying U ranch. Shorty, who had made the trip to Dry Lake on horseback that afternoon, tossed the bundle to the "Old Man" and was halfway to the stable when he was called back peremptorily. "Shorty! O-h-h, Shorty! Hi!" Shorty kicked his steaming horse in the ribs and swung round in the path, bringing up before the porch with a jerk. "Where's this letter been?" demanded the Old Man, with some excitement. James G. Whitmore, cattleman, would have been greatly surprised had he known that his cowboys were in the habit of calling him the Old Man behind his back. James G. Whitmore did not consider himself old, though he was constrained to admit, after several hours in the saddle, that rheumatism had searched him out-because of his fourteen years of roughing it, he said. Also, there was a place on the crown of his head where the hair was thin, and growing thinner every day of his life, though he did not realize it. The thin spot showed now as he stood in the path, waving a square envelope aloft before Shorty, who regarded it with supreme indifference.