The “Sources” button beside the “Download Page” button is visible only for very simple operations. How to get it for any operation?
If you have a question about the source of some information, and the information is not provided on the website, I would contact the Wolfram|Alpha team about it.
http://www.wolframalpha.com/contact.html
When using Wolfram|Alpha there is a form at the bottom of the results page for contacting them.
More complicated operations are usually the results of some computation done on other sources, so it might be more complicated to tease out what the data sources are.
Thanks Sean four answer…I used the form at the bottom to inquire about the sources, they acknowledged receiving the inquiry and I am still waiting for their response.
I was performing Fourier(Besselj(0,t)^2), I get a result but I cannot get detailed steps or the source of information.