Columbia subject headings:
Authors--History.
Celebrities--History.
Friendship--History.
Interpersonal relations--History.
Philosophers--History.
Harvard subject headings:
Authors--History.
Celebrities--History.
Friendship--History.
Interpersonal relations--History.
Philosophers--History.
Princeton subject headings:
Authors--History.
Celebrities--History.
Friendship--History.
Interpersonal relations--History.
Philosophers--History.