This spring, I was able to purchase a complete set of the A. L. Burt editions of the Linda Carlton series. All of the Burt editions are very hard to find, but most especially Linda Carlton's Perilous Summer and Linda Carlton's Hollywood Flight. I now have the complete set of Linda Carlton A. L. Burt editions.
People selling series books like to refer to less common books as "rare," or more often, "RARE," as though all capital letters make it more so. They do this all the time for Nancy Drew books that are somewhat less common printings. None of those books are remotely close to rare. Linda Carlton's Perilous Summer in the A. L. Burt dust jacket is rare.