The descriptive note comes from item A0024 in :
Cowden, Robert H.
Concert and opera singers
A bibliography of biographical materials
Compiled by Robert H. Cowden
Westport, Connecticut: Greenwood Press, c1985, 278 p.
This is what Robert H. Cowden had to say:
list of sources of bibliographic information, 801-item annotated bibliography, subject index to bibliography, summary of bibliography, index.
© Robert H. Cowden
(c) 2021. Frank Greene. All rights reserved.