About “Cantong qi”
The Cantong qi is regarded as the earliest book on alchemy in China. Its title has been rendered variously as Kinship of the Three, Akinness of the Three, Triplex Unity, and The Seal of the Unity of the Three, among other translations. Its full title, Zhouyi cantong qi, can be translated as The Kinship of the Three, in Accordance with the Book of Changes. (Summary adapted from Wikipedia, CC BY-SA 4.0.)
Some summaries adapted from Wikipedia, CC BY-SA 4.0.