All codex pages are revealed via maps purchased from art stores throughout Italy. Review your map to find each and every one. If you're having trouble finding them, use the toggles on the map to remove other categories until you're just left with the pages.
The only non-map pages are gained throughout the story, so if you've beaten the Spaniard you should have all of those. Unfortunately, it's near-impossible to be more specific, due to the number of pages available.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.