Victor Appleton was a house pseudonym used by the Stratemeyer Syndicate and its successors, most famous for being associated with the Tom Swift series of books. https://en.wikipedia.org/wiki/Victor_...
The character of Tom Swift was conceived in 1910 by Edward Stratemeyer, founder of the Stratemeyer Syndicate, a book-packaging company. Stratemeyer invented the series to capitalize on the market for children's science adventure. The Syndicate's authors created the Tom Swift books by first preparing an outline with all the plot elements, followed by drafting and editing the detailed manuscript. The books were published under the house name of Victor Appleton. Edward Stratemeyer and Howard Garis wrote most of the volumes in the original series; Stratemeyer's daughter, Harriet Stratemeyer Adams, wrote the last three volumes. The first Tom Swift series ended in 1941. In 1954, Harriet Adams created the Tom Swift, Jr., series, which was published under the name "Victor Appleton II". Most titles were outlined and plotted by Adams. The texts were written by various writers, among them William Dougherty, John Almquist, Richard Sklar, James Duncan Lawrence, Tom Mulvey and Richard McKenna. The Tom Swift, Jr., series ended in 1971. https://en.wikipedia.org/wiki/Tom_Swift
The Don Sturdy books were a series of boys' adventures that ran for fifteen volumes in the 1920s and '30s. They were produced by the Stratemeyer Syndicate for Grosset & Dunlap, and all but one of them were written by John Duffield using the Victor Appleton house name, which was famous for being applied to the Tom Swift series. The first three books introduce Don, his pal "Brick" Allison, his uncles and their household, and tell how Don is re-united with his shipwrecked family through adventures in South America and Africa after it had been assumed he'd been orphaned. The books suffer from the casual white male superiority attitude of the time but they were well-written, and were a cut above most other such series of the time, with interesting characters and many exciting adventures. (Jenny Jenks is always good for a laugh!) In this one from 1934, the next-to-last book in the series, the boys and Don's uncles go to Mongolia in search of dinosaur fossils and find a whole lot more. They have many adventures, and it's one of the most enjoyable novels in the series.