Secret Barrier X (Perry Rhodan #16) By Shols, W. W Books / Paperback Publisher: Ace Books, January 1972 Price $5.53 Free Shipping Send to a friend Collectible - Acceptable New York: Ace Books, 1972. Book 16. 16mo mass market paperback. Fair book. Inquire if you need further information. $5.53 1 in Stock at Warehouse Quantity Add Free Shipping to continental U.S. OR $1.00 per item discount if shipped to store.