Parseval–plancherel theorem

1、https://math.stackexchange.com/questions/669480/a-problem-about-laplace-transform-and-parseval-plancherel-theorem

2、https://www.solveforum.com/forums/threads/a-problem-about-laplace-transform-and-parseval%E2%80%93plancherel-theorem.340747/

3、https://handwiki.org/wiki/Plancherel_theorem#:~:text=In%20mathematics%2C%20the%20Plancherel%20theorem%20%28sometimes%20called%20the,of%20the%20squared%20modulus%20of%20its%20frequency%20spectrum.