  This paper was withdrawn by the author. The appearance of an author-written
addendum [3] to the paper [2] made our correction note [1] to that paper
superfluous and hence it is no longer available here.
  [1] Dror Bar-Natan and Ofer Ron, A Correction to "Groups of Ribbon Knots" by
Ka Yi Ng, no longer available. [2] Ka Yi Ng, Groups of Ribbon Knots, Topology
37 (1998) 441-458. [3] Ka Yi Ng, Addendum to "Groups of Ribbon Knots",
arXiv:math.GT/0310074.
