Easy to romanticize, extremely hard to document. As with anything that at the time is meant to be covert, writing it down could be what screwed you if the wrong person found it, so you don't write it down.

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There are books out there that cover this subject, but be careful what you choose because some of them are published by vanity presses, which don't necessarily have academic standards. I think John Bakeless did a book on the Culper Ring around 2000. It might be a place to start looking to mine the bibliography.