Columbia subject headings:
Arid regions agriculture--Economic aspects--Brazil, Northeast.
Industries--Brazil, Northeast.
Irrigation--Brazil, Northeast.
Seca.
Harvard subject headings:
Arid regions agriculture--Economic aspects--Brazil, Northeast.
Industries--Brazil, Northeast
Irrigation--Brazil, Northeast
Seca.
Princeton subject headings:
Arid regions agriculture--Economic aspects--Brazil, Northeast.
Industries--Brazil, Northeast.
Irrigation--Brazil, Northeast.
Seca.