I think this is a business rule that should be enforced in code. Section:Ad as M:M is already normalized.
You're already defining the B:C relationship with these two relationships: A:B - 1:M A:C - 1:M.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.