Identities for partial derivatives

Equation (7.20) is an example of a set of useful equations. If each symbol is consistently replaced by another S3mibol, we will have a useful equation for other variables besides the thermodynamic energy. We regard this as our first identity for partial derivatives, which we call the variable-change identity. 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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