The following typographical errors do not affect the
correctness of the results, but may confuse a reader.

On Page 257, delete the term "+2" in equation (10)
and delete the term "+2" in the sentence which
follows equation (10).

On Page 258, delete the phrase "to provide the term '+2'"
from the fourth sentence in the "Proof of part (b)."

Luis Goddyn and Ladislav Stacho