Thank you so much for your valuable recomdation I actually want to give an overview. Not to write on particular aspect as in contest they apply no restriction of any specific field or time era of development of science. The two scientists I mentioned work in pure(natural) and applied sciences. And yes, you are right that I should include the present development of science. Next time I will keep these things in mind. I waited for your further replies because I want to improve my writing skills. Again, thank you for your time.