Bill Maxim's enquires may be helped by use of the alternative
title for the piece: "Yours is My Heart Alone" is also known as
"You Are My Heart's Delight."  This was the title used for the
original English-language recording of the song, sung by originator
Richard Tauber.  Hope this helps.

Michael Woolf
New Zealand

 [ The German title is "Dein Ist Mein Ganzes Herz", music by the
 [ immortal Franz Lehar.  I couldn't find a date.  -- Robbie