Just for completeness, the 1990 paper referred to was by my father, Professor Alan Mackay, and was published in Modern Physics Letters B, Vol 4, No 15. I have

Just for completeness, the 1990 paper referred to was by my father, Professor Alan Mackay, and was published in Modern Physics Letters B, Vol 4, No 15. I have put up a roughly scanned copy at http://bobmackay.com/Alan/AlanCV120.pdf http://bobmackay.com/Alan/AlanCV120.pdf in case anyone is interested.