The two best books on IBM are
The Maverick and His Machine – Maney
Building IBM: Shaping an Industry and Its Technology -- Emerson W. Pugh
The book with the most flavor is
Inside IBM: The Watson Years -- William W. Simmons
The oddest book is
And Tomorrow…the World -- Rex Malik
The following are pretty much mandatory
IBM’s 360 and Early 370 Systems -- Emerson W. Pugh, Lyle R. Johnson, and John H. Palmer
IBM’s Early Computers -- Charles J. Bashe, Lyle R. Johnson, John H. Palmer, Emerson W. Pugh
Father, Son & Co. – Watson and Petre
A Business and Its Beliefs: The Ideas That Helped Build IBM – Watson (Jr.)
I liked
The Computer Establishment – Katherine Fishman
The Sun Never Sets on IBM -- Foy
The Romance Division…a Different Side of IBM -- Deloca and Kalow
how they Achieved – Lucinda Watson (daughter of T. J. Jr.) – some nuggets
I edited
IBM System/38 Technical Developments (1978 IBM General Systems Division) – ISBN – 0-933186-00-2
Indirectly about IBM
Design & Memory: Computer Programming in the 20th Century / Peter H. Huyck and Nellie W. Kremenak