Sarvepalli Radhakrishnan OM, FBA (pronunciationⓘ; 5 September 1888 – 17 April 1975; natively Radhakrishnayya) was an Indian politician, philosopher and statesman who served as the second president of India from 1962 to 1967. He previously served as the first vice president of India from 1952 to 1962. He was the second ambassador of India to the Soviet Union from 1949 to 1952. He was also the fourth vice-chancellor of Banaras Hindu University from 1939 to 1948 and the second vice-chancellor of Andhra University from 1931 to 1936. Radhakrishnan is considered one of the most influential and distinguished 20th century scholars of comparative religion and philosophy,[2][web 1] he held the King George V Chair of Mental and Moral Science at the University of Calcutta from 1921 to 1932 and Spalding Chair of Eastern Religion and Ethics at University of Oxford from 1936 to 1952.[3]
The Upanishads, the Bhagavad Gita and the Brahma Sutras are all about Vedanta, including Advaita (Vedanta). In fact, they are the three main sources about Vedanta, known as the Prasthanatrayi:
I have not read Radhakrishnan's take on the Bhagavad Gita fully. I only read parts of it, when I was a kid. We had many books in that category (Indian spirituality and mythology) lying around at home. So I read some of them.
But I have read one or two other versions of the Bhagavad Gita fully, later on, but don't remember who they were by. There are some pocket editions of the Gita available too. I used to have one. If you are into that subject, I recommend getting a pocket one (along with a bigger one), so that you can read it when you are on the go.
As for Eknath Easwaran's books, I have only read these two: Meditation and The Dhammapada. So I cannot specifically recommend any of his other books. But they are likely to be good, based on his Wikipedia page.
See Oppenheimer quote from the Bhagavad Gita after the first atomic bomb test.
https://www.google.com/search?q=Oppenheimer+quote+from+the+B....
The Gita is about Advaita.
Skip the Wikipedia article about Advaita, it is somewhat crap.
Go to deeper sources such as books by well-known people, preferably S. Radhakrishnan, 2nd President of India.
(Or at least google a bit more if don't want to or cannot buy or get the book).
https://en.m.wikipedia.org/wiki/Sarvepalli_Radhakrishnan
First paragraph from the above article about him:
Sarvepalli Radhakrishnan OM, FBA (pronunciationⓘ; 5 September 1888 – 17 April 1975; natively Radhakrishnayya) was an Indian politician, philosopher and statesman who served as the second president of India from 1962 to 1967. He previously served as the first vice president of India from 1952 to 1962. He was the second ambassador of India to the Soviet Union from 1949 to 1952. He was also the fourth vice-chancellor of Banaras Hindu University from 1939 to 1948 and the second vice-chancellor of Andhra University from 1931 to 1936. Radhakrishnan is considered one of the most influential and distinguished 20th century scholars of comparative religion and philosophy,[2][web 1] he held the King George V Chair of Mental and Moral Science at the University of Calcutta from 1921 to 1932 and Spalding Chair of Eastern Religion and Ethics at University of Oxford from 1936 to 1952.[3]