1. IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997)
2. Link for surface tension data of thiophenols: https://cutt.ly/4eyFhOC
3. J. E. Leffler and E. Grunwald, Rates and Equilibriums of Organic Reactions, Wiley, 1963 (Dover reprint)
4. J. Hine, Structural effects on equilibriums in organic chemistry, Wiley-Interscience, New York, (1975)
5. C. D. Johnson, The Hammett equation, Cambridge University Press (1973)