If you just need a quick bibliography for an essay and don't want to download anything, try ZoteroBib.
Go to https://zbib.org
In the "Cite" bar, enter either the URL for a web source, the ISBN of a book, the DOI or PMID number of an article, or the title of a source. (Numbers sometimes work better than titles.) If none of those work, you can click Manual Entry and fill in the blanks.
Your bibliography appears and shows the sources you have added. Choose your citation style using the drop-down menu on the blue Bibliography bar.
To EDIT information within a source, click on the source.
To DELETE a source, click the X button that appears to the right of the source.
To create an in-text citation or footnote, click the copy button to the right of the source and enter the page number you're citing. Then click Copy Citation and paste it into your document.
To generate your bibliography, you can choose to copy it to your clipboard and later paste into your document.
You can also share your bibliography by creating a link to it.