REF  ML134.B1 M45 1998 
Melamed, Daniel R.  An introduction to Bach studies. New York : Oxford University Press, 1998.  

Chapter 3 “Bach’s life” 3.2 Documentation-3.3 biographies of J.S Bach, especially 3.3.1 "Primary and early biographies, p. 31-32.

Mus Ref Book   ML134.H16 P37 2005
Parker, Mary Ann.    G.F. Handel : a guide to research. 2nd edition. New York : Garland, 2005.

Chapter 2. Handel’s life and his works in general:
1. Eighteenth-Century Handel Biographies p. 37-43. 
 Nice brief explanation of the issues surrounding the development of literary biography in England at this time vs Germany and the impact on sources. (p. 37) 
2. Biographies, comprehensive studies, and collections of essays: p. 43-52. Note: Parker's list is not chronological.