Concentration of Chi-Squared random variables

Let $Z$ be a Chi-squared random variable with $k$ degrees of freedom. $$\mathrm{Pr}[|\mathbb{E}Z-Z| \geq \epsilon\mathbb{E}Z] \leq 2 e^{-k\epsilon^2/8}$$

See: Concentration inequality

Reference:

1. https://www.stat.berkeley.edu/~mjwain/stat210b/Chap2_TailBounds_Jan22_2015.pdf
2. https://en.wikipedia.org/wiki/Chi-squared_distribution