Columbia subject headings:
Harvard subject headings:
Laughter--Health aspects--Congresses.
Laughter--Social aspects--Congresses.
Laughter--Therapeutic use--Congresses.
Smiling--Social aspects--Congresses.
Wit and humor in medicine--Congresses.
Wit and humor--Social aspects--Congresses.
Princeton subject headings:
European literature--History and criticism--Congresses.
Laughter in literature--Congresses.
Laughter--Social aspects--Congresses.