Hi,
Back in 2008, there was a long and interesting thread here on Former Heaven and Later Heaven Origin (https://www.onlineclarity.co.uk/friends/archive/index.php/t-3833.html), in the course of which Sparhawk and Lienshan referred to some journal articles by Schuyler Cammann that sound interesting. I was able to get copies of some of these articles online and through interlibrary loan, but was not able to acquire the last and most important:

The Origin of the Trigram Circles in Ancient China,
Schuyler Cammann,
Bulletin of the Museum of Far Eastern Antiquities, No.62, 1990

Does anyone have a copy they could share, or any information about how I could get ahold of this? I have some related articles by Cammann and Bent Nielsen that I could trade.

Thanks!

I've got it. PM me with email address.
Do you have this link? You're welcome to send anything in trade that isn't listed here with the annotation "digital library." But that's not a condition of sending you this.
http://www.hermetica.info/YixueBib.htm

Thanks Bradford! I will send you a PM with my email.