Sources:
Green Book, 2^nd ed., p. 55 (https://goldbook.iupac.org/files/pdf/green_book_2ed.pdf)
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1112 (https://doi.org/10.1351/pac199466051077)
PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 164 (https://doi.org/10.1351/pac199668010149)