Complex sentence: Another major impetus to pass the legislation was the activities of ex-CIA agent Philip Agee during the 1960s and 70s, whose book "CIA Diary" and publication "Covert Action Information Bulletin" ("CAIB") blew the cover of many agents.
Split into simpler sentences: Another major impetus to pass the legislation was the activities of ex-CIA agent Philip Agee during the 1960s and 70s. Agee's book "CIA Diary" and his publication of the "Covert Action Information Bulletin" ("CAIB") blew the cover of many agents.