B.M. Bower 
Chip, of the Flying U [EPUB ebook] 

All of the boys at the Flying U grumbled — among themselves — when they heard that the Old Man’s sister was coming to spend the summer. They didn’t want a woman at the ranch, and certainly not one who had just received a medical degree! But if they’d had an inkling of what was really going to happen, they would have done more than grumble…