Okay, you should totally add the "archive.today" extension to your Chrome-based browser, it's the best and easiest way to vault over paywalls.
https://chrome.google.com/webstore/detail/archive-page/gcaimhkfmliahedmeklebabdgagipbia
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@mcfate also available for Firefox
https://addons.mozilla.org/en-US/firefox/addon/archive-page
For academic sources, one can try Unpaywall: "When you view a paywalled scholarly article, Unpaywall automatically checks its open database of 16 million legal, open-access articles."
YMMV