There is a vast literature on the topic. You mention Sam Harris but he is not a trustworthy source for this topic and seems to misunderstand it. The crucial piece of information you would need in order to relate nondualism to academic philosophy and onwards to physics is that it endorses a neutral metaphysical position. Once you 'grok' this then you will see that all this talk of nondualism being irrelevant, vague, anti-scientific, irrational, untestable and so forth is nonsense.
One problem you face is that for the nondual philosopher the focus is on exploration and experience, not book-learning, which means that much of the literature is little help to a philosopher seeking to understand nonduality within the framework of Western philosophical thinking. Not many pursue it as an academic topic and it can be lonely field of research. One the plus side this means that researchers tend to quickly become relatively expert by general standards.
I cannot be sure what angle you wish to approach from or how much you know already, but some relevant references that come to mind would include...
Francis Bradley Appearance and Reality, George Spencer Brown Laws of Form, Radhkrishnan S The Philosophy of the Upanishads, Khenpo Gyamptso The Sun of Wisdom, Ulrich Mohrhoff The World According to Quantum Mechanics, Plotinus Enneads, Ramesh Balsekar The Ultimate Understanding
This is omitting the obvious mainstream texts such as the Baghavad Gita, the Upanishads, A Course in Miracles etc. The shortest introduction might be Know Yourself by Ibn Arabi. I happen to like the teachings of Wei Wu Wei, a friend of Spencer Brown, and there are a couple of useful websites devoted to him.
Among living philosophers I'd recommend any book by Rupert Spira. The choice is considerable but all the books say the same thing and Spira is very accessible.
Search terms would be 'nonduality', 'neutral metaphysical position', 'Unity', 'Unicity', 'Perennial philosophy', 'Middle Way', 'advaita'. The second of these may be the most productive if it's the formal aspect of nondualism that you're exploring, rather than enlightenment.
It's a little difficult to know who to mention since there are so many. If you want more targeted recommendations I'd need to know more about your particular interests.