See AACR2 Chapter 23 and the LCRIs.
United States
Base the heading on the form found in the Geographic
Names Information System (GNIS). Search using their online
form. Alternatively, use a recent edition of the Rand McNally
Commercial Atlas and Marketing Guide.
Australia
Base the heading on the form found in the Geoscience Australia Gazetteer of Australia.
Canada
Ask your NACO reviewer to query Library and Archives Canada (LAC).
Great Britain
Base the heading on the form found in the Ordnance Survey Gazetteer of Great Britain. Search using their online form.
New Zealand
Base the heading on the form found in the New Zealand Geographic Placenames Database.
Other Countries
Base the heading on the form found in the work being cataloged together with a consideration of the form found on the GEOnet
Names Server (GNS) using their online
form. Alternatively, use a recent edition of an appropriate gazetteer.
Online Help
For help with searching either the Geographic Names Information System
(GNIS) or the GEOnet Names Server (GEOnet), read the CPSO document Geographic
Names and the World Wide Web.