Sociologist and activist Frances Fox Piven is wonderful as always:
Piven's Regulating the Poor is an absolute epiphany. But you can read Poor People's Movements for a broader vision of Piven's and political scientist Richard A Cloward's rare method. Why American's Don't Vote and Why Americans Still Don't Vote are now slightly dated in terms of some of the voting obstacles they discuss, but the history is instructive, and in fact most of what they write about is timely. I was lucky enough to interview Piven a couple years ago:
Her analysis expressed in that conversation is also still instructive.