30605
At constant temperature and pressure , one must consider the Gibbs free energy , " G " , while at constant temperature and volume , one must consider the Helmholtz free energy , " A " , for the reaction ; and at constant internal energy and volume , one must consider the entropy , " S " , for the reaction .
 Gibbs, Helmholtz
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Gibbs, Helmholtz