I post a daily "Useless Quote", and often start on Wikiquote for inspiration. Wikiquote usually lists a source. From there, I go to the source, Internet Archive, or Project Gutenberg to verify it.
"Quote Investigator" (1) is a nice resource on quote origins, and "LibQuotes" (2) provides a source under the "i" button.
(From now on, I'm going to add the source details to the daily "Useless Quote".)
Links
1) https://quoteinvestigator.com/about/
3) https://libquotes.com/
Cheers!
#UselessQuote