Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page Birthday problem:

This text has been unreferenced on Wikipedia for a very long time. If you can't find a source, be bold and remove it!

"

The reverse problem is to find, for a fixed probability p, the greatest n for which the probability p(n) is smaller than the given p, or the smallest n for which the probability p(n) is greater than the given p.[citation needed]