Alternatively, check the of major Jyotish forums like LightOnVedicAstrology.com – many members share scanned chapters from out-of-print books.
: A journal article detailing the role of these nine stars and calculation methods. Navatara Chakra Basics (Scribd)
For those interested in exploring the Navatara Chakra system in more depth, we've created a comprehensive PDF guide that includes: