Provide a short summary of Ian Leslie Campbell's first three books.

Context: Ian Leslie Campbell is a British historian specialising in Ethiopia with a focus on the Italian occupation of Ethiopia. During his career, he worked together with Ethiopianist Richard Pankhurst.

His first book on Italian colonialism in Ethiopia is The Plot to Kill Graziani, an analysis of the assassination attempt on Rodolfo Graziani that took place on 19 February 1937. The Plot to Kill Graziani was declared Ethiopian Book of the Year by Richard Pankhurst, presented by the Ethiopian Broadcasting Corporation, and featured in Eland's travel series, Ethiopia Through Writers' Eyes.

His second book, The Massacre of Debre Libanos, reports the massacre of members of the Ethiopian Coptic Church in the monastery village of Debre Libanos in Italian East Africa between 21 and 29 May 1937. Campbell's findings were featured in the Italian documentaries Debre Libanos and If Only I Were That Warrior.

His third book is The Addis Ababa Massacre, an account of the atrocities following the attack on Rodolfo Graziani referred to as Yekatit 12. The book got recognition from a spectrum of international reviewers, and in 2018 became available in an Italian edition, Il massacro di Addis Abeba, raising a debate in Italy about the responsibilities of Italian colonialism.

Answer: Ian Leslie Campbells first three books were "The Plot to Kill Graziani", "The Massacre of Debre Libanos", and "The Addis Ababa Massacre". Each of the books are about violent attacks on people.