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Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Deepak singh 1
https://www.google.com/url?sa=t&source=web&rct=j&url=http://ramanujan.math.trinity.edu/polofsson/teach/Book.pdf&ved=2ahUKEwiR9Yn2l5jrAhWK4zgGHV5kBgIQFjAJegQIBhAB&usg=AOvVaw3CpGBAsoXGA2kdIOWorexQ or go through this link