'as per Newton, Leibniz et al...' isn't good enough? Seriously though: if it is indeed true that you need to justify it this way, that is insane: this is just

'as per Newton, Leibniz et al...' isn't good enough? Seriously though: if it is indeed true that you need to justify it this way, that is insane: this is just basic calculus. Do you have to justify every single statistics calculation also? Do you have to say 'as per Whoever et al' every time you calculate the standard deviation of something? What referee would object to 'estimating the area using the trapezoidal rules gives us...'? (note that this paper was purely about the CALCULATION of the area, not justifying whether or not the area is a useful thing to know)