Update bibliography

docs/txt/BIBLIOGRAPHY.md

@@ -7,8 +7,10 @@
 ## Polynomials
 - Hirst, H. P., & Macey, W. T. (1997). Bounding the Roots of Polynomials. The College Mathematics Journal, 28(4), 292–295. https://doi.org/10.2307/2687152
 
+## Statistics
+- W. J. Metzger. (2020). Statistical Methods in Data Analysis. Radboud Universiteit Nijmegen.
+
 ## Pseudorandom and quasirandom generators
 - Morokoff, W J, & Caflisch, R E. Quasi-Monte Carlo integration. United States. https://doi.org/10.1006/jcph.1995.1209 
 - [The Unreasonable Effectiveness of Quasirandom Sequences](http://extremelearning.com.au/unreasonable-effectiveness-of-quasirandom-sequences/)
 - [xoshiro / xoroshiro generators and the PRNG shootout](https://prng.di.unimi.it/)
-