Some areas of the body are naturally darker than others - for all skin colours. The dark areas simply appear darker in coloured people. If this embarrasses you, you could apply a mild peroxide to the elbows and knees.
But what works really well over a time period is (a) do not rest your elbows on a hard surface, for long periods of time...the skin gets thicker there and darker, and (b) after a shower, always, always, use a moisturising cream in the dark area. Periodically, you could also use an exfoliating agent to make the skin softer in such areas. This is not a malady, so don't expect a cure.
This is only a beauty treatment. More.
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.