Available from various publishers including Astro Mantra and Great E Pujari .
The term "251" usually refers to a count—often a specific number of recitations, distinct yantra designs, or a compilation code used by the publisher. In the context of popular Tantric paperbacks often sold in Indian bazaars (particularly from publishers like Gita Press or specialized Tantric presses in Delhi and Kolkata), this book is marketed as a compendium.
: While a single "full PDF" version of the exact Gopal Raju book is rarely available for free due to copyright, similar collections and fragments of rare yantras can be viewed on or searched for on the Internet Archive specific construction methods