Columbia subject headings:
Animal communication.
Apes--Behavior.
Children--Language.
Sign language.
Harvard subject headings:
Animal communication--Congresses
Animal communication.
Apes--Behavior
Apes--Behavior--Congresses.
Children--Language
Children--Language--Congresses
Sign language acquisition--Congresses.
Sign language.
Princeton subject headings:
Animal communication.
Apes--Behavior.
Children--Language.
Sign language.