The Aunt Jane's Nieces series was written by L. Frank Baum under the pseudonym of Edith Van Dyne - the same name he used for the Flying Girl and Mary Louise series. Baum wrote 10 books about the nieces, and this series for teens was as popular in its day as the Oz books.
Reilly & Britton experimented with a couple formats before settling on a look for the books. The first title had a rather severe binding, with very little ornamentation. With the second title, a larger format was tried, with a floral design and more extensive gilt stamping - I personally like this format, it gives the book a bit more presence. Finally, a simpler cover was used in tan cloth with no gilt stamping. This style won out, and first editions of the remaining titles in the series were published this way. Below, I show the rest of the titles - three in dustjackets.