For my 3 non fiction books :
- Hidden Treasure
- Hidden Depths
- Spy, Spy Again
I carefully researched primary sources and books written by respected experts and historians. (A primary source is a document or an account written during the time that you are studying. Pictures and photographs of that time are also primary sources.) Then I photocopied all the research and slotted them into files in a cardboard box, which I stored under my art desk.
WARNING! If you have a rotten cat like I do, beware! My cat shredded chapter three's research for Spy, Spy Again. (He does a similar trick with rolls of toilet paper.) But it could have been much worse. A former cat (he'd dead now- no I didn't kill him, he died of old age) thought that a box of my beautiful watercolour art was a kitty toilet.