|Title : An Analysis of Various Versions of A.M. Toplady's Rock of Ages, Cleft For Me (1774-2001)
|Author : Samuel J. Rogal
This book is exactly what it claims to be, an exhaustive study of how (and why) the text of "Rock of Ages" has changed over the years. there is also a useful biography of Toplady.
If you are discussing the form of "Rock of Ages" you prefer you really need this good (but eye wateringly expensive) book.