• The Clausius-Clapeyron Equation (Spakovszky, web.mit.edu)
• Coplovici, Lucian O. et al., 2005, Chemosphere, 61, pp 1390–1400. They refer 44.3 kJ/mol for limonene.
• Weisstein, Eric, "Least Squares Fitting." From MathWorld—A Wolfram Web Resource.