Two additional sources:

Fran Lisa Buntman, Robben Island and Prisoner Resistance to Apartheid. Cambridge University Press (2003)
http://www.amazon.com/Robben-Island-...28/ref=ed_oe_p

Kieran McEvoy, Paramilitary Imprisonment in Northern Ireland: Resistance, Management, and Release, Oxford University Press, (2001)
http://www.amazon.com/Paramilitary-I...5717446&sr=1-2

The Buntman book is excellent and develops a theory of prisoner resistance (referred to as a 'continuum'); i.e. the different motivations and means by which 'political' prisoners exist in prison; it is also a useful account of how the ANC leadership prepared for its eventual move into government.

The McEvoy book is a slightly different book, not developing quite such a high level set of conclusions, but I don't think there is a single better detailed examination of PIRA's (and others) activities in prison.