Source: Statistics at Square One (BMJ online)
How to access: This is free to access from the above link.
Contents: This is one chapter in Statistics at Square One (online). This section discusses the idea of Fisher's exact test and how to calculate the p-value.
Example(s) used in this: Association between dropping zone and injury in parachute training of soldiers
Prior math/stat knowledge to fully understand matrials: Combinatorics and Hypothesis testing.