A few seminal articles give an overview of Second-Wave rap:
Title: Hip-hop Madness.
Author: Allen, H
Publication Info.: Essence; Apr89, Vol. 19 Issue 12, p78, 6p, 1 bw
Title: The Group Run-D.M.C. Defends Rap Music.
Publication Info.: New York Times; 9/19/1988, p19, 0p
Title: What's Behind the Rise of Rap?
Author: McKinney, R.E.
Publication Info.: Ebony; January 1989, Vol. 46 Issue 3, p66, 4p, 1 color
Title: Rap Music, Despite Adult Fire, Broadens its Teen-Age Base
Author: Palmer, R.
Publication Info.: New York Times; 9/21/1986, p23, 0p