Shiva Sutras, Vijnana Bhairava, Pratyabijna Hridaya, Paratrisika Vivarana and Spanda Karikas from my opinion are the profoundest and the most essential Anuttara Trika of Kashmir Shaivism scriptures. Spanda is the Creative Throb, Divine pulsation, the Original Vibration from which the Universe originates. If one is serious about finding the the Ultimate Truth of Reality then this book can give you a great insights. Five Stars
Here is one of the most valuable reviews
"Tantric Science of the Sacred Tremor
Spanda-Karikas is a classic masterpiece of Shaivite philosophy/cosmology/speculation. Jaideva Singh's careful translation of this treasured text makes it available to Western/English speaking seekers in a helpful, illuminating and comprehensive manner without sacrificing even the slightest amount of its original profundity and power. This is a masterful presentation of Spanda-Karikas, both enlightening and praiseworthy. Each verse is presented first in its original Devanagari with accompanying English translation followed by extensive exposition by the great Shaivite saints Vasugupta and Ksemaraja. Jaideva Singh also includes copious and incredibly helpful notes on the text along with his own commentary on each verse. A must-have for any student of Shaivism/Hinduism. Without a doubt, an enlightening and fascinating journey into the Shaivite concept of Spanda and consciousness that will be a true boon to any earnest spiritual seeker. Though I do feel the need to include a word of caution to some readers. This text is by no means whatsoever "Hinduism-lite". Spanda-Karikas is a journey into the philosophical/speculative heart of Hindu thought. If you are just starting into Hinduism or your interest is more casual in nature I would recommend starting with Bhagavad Gita or the principal Upanishads as these may be more digestible and comprehensible to newcomers. This is not to discourage anyone, but I definitely suggest you approach this text after having already established a reasonable familiarity with the philosophical concepts of Hinduism, otherwise you may find yourself struggling just to keep your head above water in the ocean of complex terminology and concepts presented here."