Your problem is that the function has been declared but not implemented. Whether it's in the same file, a . Cpp file, or library, the body of the function needs to be there before you can use it.
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.