S.H. Hall’s “Scripture Studies” volume four (1960) is now online. In this book, Hall gives three written replies to the myriad of arguments used to justify instrumental music in worship. One of them is a synopsis of his debate with H.K. Pendleton (who claimed IM was inherent in the word psallo), another is a written debate with R.C. Harrell (who argued it is merely an expedient), and the last is a reply to a tract which claimed instrumental music is scriptural.
www.GravelHillchurchofChrist.com/ebooks.htm (they are alphabetized by author).