Since it was just mentioned on the SEELANGS LIST, some of you may want this reference: GOLAB, Zbigniew. "The Initial X- in Common Slavic: A Contribution to Prehistorical Slavic-Iranian Contacts." In <American Contributions to the VII International Congress of Slavists, Warsaw, August 21-27, 1973>, vol. 1, pp. 129-56. Don Dyer