I have everything by Piper excluding "Murder in the Gunroom". "Space Viking" is sort of my "Catcher in the Rye". I can't enter a book store without looking for a copy. I have first editions of "Space Viking" and "Lord Kalvan" along with numerous copies of Viking and "Junkyard Planet". Personally, "The Cosmic Computer" aka "Junkyard Planet" is one of my favorite books.