I have studied Ramana for over 40 years and Nisargadatta for 30. There are few books I can recommend about Ramana because I don't feel many really grasp Ramana. But I do recommend Michael James book available for free download from his website HERE.
Now expect to spend some time to feel this book to understanding.
Then, at the same time read Prior to Consciousness, or Consciousness and the Absolute, as well as Self-Knowledge and Self Realization by Nisargadatta Maharah available under Resources on my website at:
Now be prepared to continue study of these books for three years, gradually getting deeper and deeper, with interspersed hammer blows of awakening. When you then dry out as a result of energetic and/or dispassionate observation and investigation, download my free book Self-Realization and Other Awakenings from my website and switch tofeeling for the I Am inside your body and your sense of presence, accepting and loving all that arises as a result of now attending to feelings, emotions, and energies.
This will bring you to Self-Realization. Email me, ask questions. This is the Advaita/Tantric combo that keeps your path wet and wild, while getting deeper and deeper.