Cuemath
Cuemath: Permutations and Combinations
Takes a look at the different situations where to use permutation or combination and the difference between them. Includes definitions, solved examples, and practice questions.
Wolfram Research
Wolfram Math World: Topics of Permutation
This MathWorld site is a lite to link to a multitude of sites involving permutations. Look through to find your specific needs. If you are looking at this site with regards to a probability and statisics class you will probably want to...