Where does SKEW Excel equation come from? I need to quote Excel's skew equation in a paper but I couldn't find any information about this equation: 

$n$: size of the population 
$s$: standard deviation 
signed $x$: mean 
Does anyone know if in statistics this equation is known with some name so I could add a quote on the paper indicating where the equation comes from? 
here's the link of excel's skew article: 
https://support.office.com/en-us/article/SKEW-function-bdf49d86-b1ef-4804-a046-28eaea69c9fa
 A: One definition of skewness is as the third standardized moment of a distribution: the ratio of the third central moment to the cube of the standard deviation (the square root of the second central moment):
$$
\frac{\operatorname{E}{(X-\operatorname{E}{X})^3}}
{\left[\operatorname{E}{(X-\operatorname{E}{X})^2}\right]^\frac{3}{2}}
$$
The corresponding property in a sample (or finite population) is given by
$$
\frac{\sum (x - \bar{x})^3/n}{\left[\sum (x - \bar{x})^2/n\right]^\frac{3}{2}},
$$
the Fisher—Pearson third standardized moment coefficient, or the Fisher–Pearson coefficient of skewness, or suchlike.
In samples of i.i.d. observations, this statistic is a consistent, though not unbiased, estimator of the skewness of the distribution from which the samples are drawn, provided of course that the first 3 moments exist. Now, the estimators of the second & third central moments that appear in the denominator & numerator are also consistent, & with biases that depend only on the sample size, $\frac{n-1}{n}$ & $\frac{(n-1)(n-2)} {n^2}$ respectively: substituting the de-biased estimators into the ratio results in
$$
\frac{\frac{n^2}{(n-1)(n-2)}\sum (x - \bar{x})^3/n}
{\left[\left(\frac{n}{n-1}\right)\sum (x - \bar{x})^2/n\right]^\frac{3}{2}}
=
\frac{n}{(n-1)(n-2)}\cdot\sum\left(\frac{x - \bar{x}}
{s}\right)^3
,$$
where $s$ is the sample standard deviation; & this is known as the adjusted Fisher–Pearson third standardized moment coefficient, &c. (I can't say I see the motive behind the adjustment, as it still doesn't give an unbiased estimator of skewness.)
See https://en.wikipedia.org/wiki/Skewness#Sample_skewness & the references given there: Joanes & Gill (1998), "Comparing measures of sample skewness and kurtosis", J. Royal Stat. Soc. D, 47 (1); &
Doane & Seward (2011), "Measuring skewness: a forgotten statistic", J. Stat. Educ., 19 (2).
