Bartlett&#x27;s Familiar Quotations is one of the classic gold standards. It&#x27;s reasonably well-sourced, and it separates out &quot;attributed&quot; but uncomfirmed remarks. It&#x27;s not as comprehensive as the online sites, since it&#x27;s edited as a physical book, but it&#x27;s pretty reliable:<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Bartlett%27s_Familiar_Quotations" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Bartlett%27s_Familiar_Quotatio...</a><p>It&#x27;s an American work, so I don&#x27;t have a good sense for how well it covers other regions&#x27; quotations.