Columbia subject headings:
Harvard subject headings:
DeLong, Dwight Moore, 1892---Congresses.
Insect-plant relationships--Congresses
Leafhoppers--Congresses.
Planthoppers--Congresses.
Princeton subject headings:
DeLong, Dwight Moore, 1892-1984--Congresses.
Insect-plant relationships--Congresses.
Leafhoppers--Congresses.
Planthoppers--Congresses.