Columbia subject headings:
Harvard subject headings:
Agriculture--Tropics--Abstracts--Periodicals.
Agriculture--Tropics--Indexes--Periodicals.
Tropical crops--Abstracts--Periodicals.
Tropical crops--Indexes--Periodicals.
Princeton subject headings:
Agriculture--Tropics--Abstracts--Periodicals.
Agriculture--Tropics--Indexes--Periodicals.
Tropical crops--Abstracts--Periodicals.
Tropical crops--Indexes--Periodicals.