It's not a scientific paper but this book is the most extensive resource I'm familiar with on the history of Bwiti through a Western anthropological lens. Discussion of iboga itself is somewhat limited given the scope of Bwiti and the size of the book, but there's still a ton of relevant information.
"Consciousness grows in spirals." --George L. Jackson
If you can just get your mind together, then come across to me. We'll hold hands and then we'll watch the sunrise from the bottom of the sea...
But first, are you experienced?