https://doi.org/10.1351/goldbook.R05176

The probability that a reaction occurs when two particles undergo a collision. If N c is the number of collisions occurring in unit time, and N r the number of reactions occurring in unit time: P r = N r N c.*Source: *

PAC, 1996,*68*, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 184 (https://doi.org/10.1351/pac199668010149)

PAC, 1996,