Columbia subject headings:
John, Augustus, 1878-1961.
John, Gwen, 1876-1939.
Painters--Wales--Biography.
Siblings.
Women painters--Wales--Biography.
Harvard subject headings:
John, Augustus, 1878-1961--Exhibitions.
John, Gwen, 1876-1939--Exhibitions.
Princeton subject headings:
John, Augustus, 1878-1961--Exhibitions.
John, Gwen, 1876-1939--Exhibitions.