Grosset Dunlap. Copyright 1964. Print run - the first, 1964. Farah-coded 1964A-1. #41 in the series. Picture cover rear last title is itself. There are no internal book listings. Black/white multiscene endpapers. Original 20-chapter text, never revised, was authored by Harriet Stratemeyer Adams using the house pseudonym "Carolyn Keene." Not all, but some, of the first editions had a tri-fold "who's who" quiz advertisement made of stiff paper bound in between the rear free endpaper and the blank page before it. This copy of the book has that insert. It was a way for the publisher to advertise series books now that dust jackets, with their rear and flap ads, were no longer used. The reader was invited to check off desired books from various Stratemeyer Syndicate series and non-Syndicate series, and mail in a detachable post card order form. This one is pristine, not having been marked, soiled or torn in any way. It is regarded by Farah and collectors as "scarce," appearing in only a few picture cover volumes, including a Cherry Ames volume and a Tom Swift volume, among others. In Farah's Guide, 12th printing, the value set at a first edition #41 in very good condition with the tri-fold was set at $100.00. Which brings us to the condition of this book, which is not as good as the tri-fold. While overall sturdy and not written in, it has some noticeable flaws. About a half inch in from the left, the front cover has a vertical slice indentation, as if someone had cut a slice of bread using the book as a cutting board. There is significant spine side wear, particularly at the right of the sleuth symbol. Spine is slanted. Edgewear and corner bumping. At the top of the front cover edge, there is wear through to the board. Side page block is soiled. A track is forming between the copyright page and table of contents page. Small spot of dark blue ink bleed from the inked page block top carries through to the first two chapters. Despite all that, it's still a conversation piece and a pretty strong book.