Columbia subject headings:
Harvard subject headings:
Allegheny River (Pa. and N.Y.)
Monongahela River (W. Va. and Pa.)
Ohio River--Description and travel.
Ohio River--Navigation.
Pilot guides--United States.
Princeton subject headings:
Allegheny River.
Mississippi River--Description and travel.
Mississippi River--Navigation.
Monongahela River (W. Va. and Pa.)
Ohio River--Description and travel.
Ohio River--Navigation.