This research should include three distinct sections:

Section 1: Who were the agencies conducting intelligence operations in Northern Ireland during The Troubles (between 1968 and 1998) and why did they conduct them? 
Section 2: How legal were they? What UN laws or protocols did they contradict or abide by? Who authorised them? Were they legitimate? What did other countries say about them? Who condemned and who commended?
Section 3: What has this meant for the future of Northern Ireland and intelligence operations around the world? What has become of their legacy?

The readings given should aid in direction but only for the introduction and first section. Further material will be required to compile section 2 and 3.