https://www.google.com/books/edition/India_Traders_of_the_Middle_Ages/WMj5aFA3bjQC?hl=en

I've seen a few references to Goitein's "India book". This seems to be the referent, which somehow never seems to be called by title, even in contexts of academics who love citations. Is it shorthand? Was the book published posthumously? (2008, so yes)

Wikipedia calls it out as such as well...

India Traders of the Middle Ages: Documents From the Cairo Geniza (ISBN 9789004154728), 2008 (also known as "India Book")