Hmm. That's a really good question, and I think possibly a hole in the scholarship--there's a lot of stuff that's known anecdotally, but I don't know that anyone's ever put it all together in English. Aside from ransacking the citations in the articles in Mechademia 2, I'd actually suggest asking rushthatspeaks, who's working on a history of shoujo and knows way more about it than I do.

I have no idea whether its issues are online at all or not, but the place I'd think to find articles would be The Comics Journal, I think is the name. Wherever Matt Thorn published his interviews with Hagio Moto.