Which source would best a historian understand how the great chicago fire affected families?

The best source would be a person who lived through the event (best of the best)  (survivor pretty much)
A close family relative ( next to best)
Trustworthy sources of information (last of the best maybe)
*some newspapers exaggerate what goes on, as seen in the article for "the battle of Iwo Jima". So newspapers aren't really a good source

hope this helps