A new book by G. Beinhundner on the Cetoniinae of Africa, 2017, 1199pp:
"It is huge book including all the African Cetoniinae (excl. Madagascar) except for three species which are known from type specimens only. All the available colour or shape varietes are shown on colour pictures. All the important references to each species are given. The book was published by the author himself as digital print and carefully hard bound."
It's not cheap at 320 Euros but from the plates figured it appears worth the investment.