Columbia subject headings:
Families--Research--History--19th century.
Social evolution--Research--History--19th century.
Harvard subject headings:
Bachofen, Johann Jakob, 1815-1887.
Families--Research--History--19th century.
McLennan, John Ferguson, 1827-1881.
Morgan, Lewis Henry, 1818-1881.
Social evolution--Research--History--19th century.
Princeton subject headings: