blish says in his foreword that all of the magical works and quotations mentioned in the text actually exist, as do the magical symbols reproduced, and "there are no "necronomicons" or other such invented works". this is true insofar as blish did not invent any of the works himself. "the book of the sayings of tsiang samdup" was invented by talbot mundy; it is the supposed source of the quotations at the beginning of each chapter in his novels "om — the secret of ahbor valley" (1924) and "the devil's guard" (1925).