Columbia subject headings:
Marine accidents--Maine--Portland.
Marine accidents--United States.
Merchant mariners--Drug testing--Maine--Portland.
Merchant mariners--Drug testing--United States.
Transportation accidents--Maine--Portland.
Transportation accidents--United States.
Harvard subject headings:
Princeton subject headings:
Marine accidents--Maine--Portland.
Marine accidents--United States.
Merchant mariners--Drug testing--Maine--Portland.
Merchant mariners--Drug testing--United States.
Transportation accidents--Maine--Portland.
Transportation accidents--United States.