Children's Writer & Sometimes Poet
You write about what you already know, right? But, you also write about things you want learn more about. Admittedly, after researching this topic I may be more confused than when I started. Let me see if I can work it out!

The easy part: Historical Fiction
Examples
Goodreads has a list of 653 of the Best Children’s Historical Fiction.
The hiccup: (and something I learned in my research!)
In order for a story to be historical fiction, it must be historical to the author. If I were writing a novel set in London 2013 about a girl who desperately wanted to become a nanny for the future king, it would be contemporary fiction right? In twenty years it would still be contemporary fiction from a different time. So the argument then is books like those written by Jane Austen, Charles Dickens, and Laura Ingalls Wilder would not be historical fiction because at the time they were written they were contemporary fiction.
What do you think? Agree? Disagree?
Onto documentary novel – the waters get a little more muddy for me here.
I have seen three different definitions for documentary novel.
1. True event + real people told in a narrative format. (plot, dialogue, characterization)
until . . .
And this one I have read. It is written in verse and alternates between the two lead characters, who are historical figures. I spoke to Patricia regarding this book. It is as historically accurate as is possible considering the main characters have both passed away. Through in depth interviews with friends and family she was able to ascertain specific details to the events of the story. The area that the author must take a little liberty is when there is dialogue.2. A historical fiction novel that includes articles of history within the pages. These may include quotes, advertisements, and the like.
3. A historical fiction novel in which the format appears like non-fiction articles.
What kind are you writing? Historical fiction or documentary novel? How do you know?