Columbia subject headings:
Railroads and state--Paraguay--History--20th century.
Railroads--Paraguay--History--20th century.
Railroads--South America--History--20th century.
Harvard subject headings:
Railroads and state--Paraguay--History--20th century.
Railroads--Paraguay--History--20th century.
Railroads--South America--History--20th century.
Princeton subject headings:
Railroads and state--Paraguay--History--20th century.
Railroads--Paraguay--History--20th century.
Railroads--South America--History--20th century.