Study, Tutorial, Entropia

https://de.ifmo.ru/bk_netra/page.php?dir=1&tutindex=13&index=7&layer=3

Normal, Distribution, Nist

https://www.itl.nist.gov/div898/handbook/index.htm

https://www.itl.nist.gov/div898/handbook/eda/section3/eda36.htm

https://www.itl.nist.gov/div898/handbook/eda/section3/eda366.htm

Variation, Gelfand, derivatives

https://scask.ru/r_book_varc.php?id=7

https://stepik.org/lesson/183290/step/1