Presentation signature from Victor Appleton II to Dr. Fred L. Whipple, an expert on comets who was a consultant on Tom Swift and the Mystery Comet (1966).

When collecting modern first printings, the typical desire is to obtain a first printing of a book in fine condition that is signed by the author.  Sometimes these copies are the only ones that will sell at all.  With juvenile series books, this is usually not possible because there were relatively few occasions to meet […]