Columbia subject headings:
Merchant marine--Licenses--United States.
Merchant mariners--Licenses--United States.
United States. Coast Guard--Rules and practice.
Harvard subject headings:
Merchant marine--Licenses--United States.
Merchant mariners--Licenses--United States.
United States. Coast Guard--Rules and practice.
Princeton subject headings:
Merchant marine--Licenses--United States.
Merchant mariners--Licenses--United States.
United States. Coast Guard--Rules and practice.