Desauvage, S., Daffe, V., & Fastrez, J. (1982). The Role of the Resonance Energy in the Tautomerism, Acidity and Mechanism of Hydrolysis of Heterocycles. Societes Chimiques Belges. Bulletin, 91(5), 387. https://doi.org/10.1002/bscb.19820910546 (Original work published 1982)