Columbia subject headings:
Opera--Germany--19th century.
Singers--Germany--Biography.
Vogl, Heinrich, 1845-1900.
Vogl, Therese, 1845-1921.
Harvard subject headings:
Opera--19th century
Vogl, Heinrich, 1845-1900.
Vogl, Therese, 1845-1921.
Princeton subject headings:
Opera, German--19th century.
Opera--Germany (West)--Munich.
Vogl, Heinrich, 1845-1900.
Vogl, Therese, 1845-1921.