I found this book from my MBA days and am using it to describe my Methodology in the Proposal. I haven’t seen many other books about the subject so I can’t benchmark it, but I found this useful and easy to follow. I also think the structure is suitable for referring to separate sections as and when they’re needed.
The one I have is the 3rd edition. I will probably borrow the 5th edition from a library to see the updates.
It’s not cheap! Amazon link here.