Columbia subject headings:
Bolivia--Discovery and exploration.
Gran Chaco.
Pilcomayo River.
Harvard subject headings:
Bolivia--Discovery and exploration.
Discoveries in geography--Bolivia.
Gran Chaco.
Pilcomayo River.
Princeton subject headings:
Bolivia--Exploring expeditions.
Gran Chaco--Exploring expeditions.
Paraguay--Exploring expeditions.
Pilcomayo River (Bolivia)--Discovery and exploration.