Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
In the reference list of this article by W Dale Dauphinee (30 October, pp 1188-90), reference number 8 should have been listed as number 7, and number 7 should have been listed as number 8.
