temperature are fixed, respectively. The five most well known potentials are: where is the temperature, the entropy, the pressure, the volume, the chemical potential, the number of particles in the system, and is the count of particles types in the system. Thermodynamic potentials can be derived from the energy balance equation applied to a thermodynamic system. Other thermodynamic potentials can also be obtained through Legendre transformation. Axiomatic thermodynamics Axiomatic thermodynamics is a mathematical discipline that aims to describe thermodynamics in terms of rigorous axioms, for example by finding a mathematically rigorous way to express the familiar laws of thermodynamics. The first attempt at an axiomatic theory of thermodynamics was Constantin Carathéodory's 1909 work Investigations on the Foundations of Thermodynamics, which made use of Pfaffian systems and the concept of adiabatic accessibility, a notion that was introduced by Carathéodory himself. In this formulation, thermodynamic concepts such as heat, entropy, and temperature are derived from quantities that are more directly measurable. Theories that came after, differed in the sense that they made assumptions regarding thermodynamic processes with arbitrary initial and final states, as opposed to considering only neighboring states. Applied fields See also Thermodynamic process path Lists and timelines List of important publications in thermodynamics List of textbooks on thermodynamics and statistical mechanics List of thermal conductivities List of thermodynamic properties Table of thermodynamic equations Timeline of thermodynamics Thermodynamic equations Notes References Further reading A nontechnical introduction, good on historical and interpretive matters. Vol. 1, pp. 55–349. 5th ed. (in Russian) The following titles are more technical: External links Thermodynamics Data & Property Calculation Websites Thermodynamics Educational Websites Biochemistry Thermodynamics Thermodynamics and Statistical Mechanics Engineering Thermodynamics – A Graphical Approach Thermodynamics and Statistical Mechanics by Richard Fitzpatrick Energy Chemical engineering