I rarely run into names of singers that I haven't seen before, but Madame
Bozena Ruk-Focic is one. She sings the part of Lady Macbeth's
lady-in-waiting in a 1964 Salzburg performance of Macbeth with DFD and Grace
Bumbry, which can be heard this evening at 6 on Radio Oesterreich - see
operacast.com for details.
After Googling, I learned that Madame Ruk-Focic was a Croatian soprano,
1931-2010, who apparently enjoyed an illustrious career in her hometown
Zagreb. She has three cuts on YouTube - Mi chiamano Mimi, Timor di me, and
the Willow Song - all worth hearing. The voice production is uneven, but
there are moments of great beauty, especially the soft high notes. Anyone
out there ever hear of her?