: The journey begins with the ancient Vedic origins of Siva as Rudra , exploring his growth through the Agamas (scriptural texts). It explains how the formless (Nirakar) Divine manifest into symbols we can see.
If you are looking for specific aspects of Shaiva philosophy or different authors, these are also highly regarded: Sri Vidya Kosa S. K. Ramachandra Rao - Internet Archive
: Includes extensive source materials, hymnology, and specific worship rituals. PDF & Access Options
: Exploration of the Linga (aniconic) and 24 Lilamurthi (iconic) forms.