Columbia subject headings:
Frederick II, King of Prussia, 1712-1786.
Voltaire, 1694-1778--Friends and associates.
Harvard subject headings:
Authors, French--18th century--Biography
Frederick II, King of Prussia, 1712-1786.
Voltaire, 1694-1778--Friends and associates.
Princeton subject headings:
Frederick II, King of Prussia, 1712-1786--Friends and associates.
Voltaire, 1694-1778--Friends and associates.
Voltaire, 1694-1778--Travel.