The Seven Churches of Revelation 2-3
The Seven Epistles of Christ,
by Taylor G. Bunch.
The Seven Churches of Asia, by Robert Murray M’Cheyne.
“What is the Laodicean Problem?” by Cecil E. Maranville.
"Seven Churches of Revelation", by Richard C. Nickels.
The Letters to the Seven Churches of Asia by William M. Ramsay, 1904.