Perusing - as you do - and came across this compilation :
📚 The Hitchhiker’s Guide to the Galaxy: A Trilogy in Four Parts by Douglas Adams (sorry - Amazon link - couldn’t find this edition on MicroBlog)
It reminded me of a much older ‘trilogy’, penned by one Spike Milligan - who around book 5 wrote something like
Number 5 in the increasingly misnamed ‘War Trilogy’.