Yantra, Mantra Tantra Vidhya : Dediyar, Vladimir : Free Download, Borrow, and Streaming : Internet Archive. Internet Archive Mantra Tantra Yantra Vigyan July 1981 - Internet Archive
: A comprehensive collection by Gandhar Acharya Kunthu Sagar Ji in Sanskrit-Hindi, covering a wide range of Mantras and Yantras. Yantra Mantra Kalp Sangrah Internet Archive Hindi Tantra Mantra Yantra Books Free Pdf
: Authored by Pt. Laxmi Narayan Sharma, this book details the practical application (sadhana) of various mantras and tantric rituals. Anubhut Yantra Tantara Mantra Yantra, Mantra Tantra Vidhya : Dediyar, Vladimir :
: A focused collection exploring the structural and spiritual significance of mystical diagrams and spells. Mantra Tantra Sadhana (by Pt. Laxmi Narayan Sharma) Laxmi Narayan Sharma, this book details the practical
A high-level scientific approach to Tantra available in multiple formats.
For Hindi Devanagari text, download the "PDF with text" version if available. This allows you to copy-paste mantras (though always cross-check with original scans).