Three Principles Resources:
For those wishing to truly deepen their understanding of The Three Principles, there are many resources available.
As a general rule of thumb I would encourage you strongly to pursue your searching with the works of Sydney Banks, the pioneer of this understanding.
Guy Fisher, over at Sydney Banks Products, has all of Syd’s works available and is very rapid for EU addresses. When ordering, my personal clients can benefit from a special coupon code giving them a reduction on all items (except items on sale). Available are the books, audios and videos that Syd left us.