6. Data sources and estimation of thermodynamic quantities

Clearly, any user of a physical theory (and therefore of thermodynamics) needs access to the numerical values of the quantities involved in that theory, in order to solve a practical problem. To do this, he or she can turn to data banks, either on paper or accessible by computerized search. If the numerical value cannot be found in this way, estimation methods can be used to provide it with a precision that is often perfectly compatible with that of other data and calculation approximations.