I don't know if you would classify this as a "maths research book", but it's a wonderful personal and emotional description of the process of math discovery: B

I don't know if you would classify this as a "maths research book", but it's a wonderful personal and emotional description of the process of math discovery: Birth of a Theorem - A mathematical adventure by Cedric Villani https://us.macmillan.com/books/9780374536671/birthofatheorem https://us.macmillan.com/books/9780374536671/birthofatheorem