In this story, Don Rosa mainly uses references to Barks' "A Spicy Tale" (W US 39), "Forbidden Valley" (W DD 54), and "Trail of the Unicorn" (W OS 263). There are a lot of redrawn panels from "Forbidden Valley" :
First, Donald Duck's rememberings about what happened with the Javloro Indians ( The first panel is a melting of two other panels)
Then, panels where the Nephews remember about when they destroyed the Javloros's village :
Then, the arrival in the valley :
And finally, the valley itself :