re: Operational amplifier -what book explains internals?
When I studied electronic circuit design, Gray/Meyer, Analysis and Design of Analog Integrated Circuits was our basic text book. These days, I would still consider the fifth edition by Gray, Hurst, Lewis, Meyer. Supplemented by CMOS chapters, focusses on bipolar technology.
re: Operational amplifier -what book explains internals?
I'd confirm FvM's suggestions and maybe add Electronic Fundamentals & Applications (John Ryder) if it's
more theoretical than practical manufacture you're interested in. It covers a wide range of topics though.
Looking at my shelf I see mine's dated '74 ... damn I must be getting old !