Columbia subject headings:
Harvard subject headings:
Chad, Lake, Watershed--Social life and customs--Congresses.
Human ecology--Chad, Lake, Watershed--Congresses.
Public health--Chad, Lake, Watershed--Congresses.
Traditional medicine--Chad, Lake, Watershed--Congresses.
Princeton subject headings:
Chad, Lake, Watershed--Social life and customs--Congresses.
Human ecology--Chad, Lake, Watershed--Congresses.
Public health--Chad, Lake, Watershed--Congresses.
Traditional medicine--Chad, Lake, Watershed--Congresses.