Suzette,
Hi.
As I said, the Triskeliion is quite similar - it is possible the Triskelion preceded the Antahkarana so perhaps researching the Triskelion might yield some other sources.
It also struck me, looking at the Antahkarana (or angular Triskelion) that it is a three-legged version of the swastika which is alleged to have been in use in China and elsewhere at least 3000 years before the christian era so predates the Ankh in Egypt as well
Does this get you closer to a source? Hard to say. You will have to do the research I guess. But remember, it is only a symbol and has no inherent 'powers'. Power comes from Intention and attribution.
Cheers,
RC
