https://forums.opera.com/topic/35100/open-in-sumatra-pdf-and-djvu-reader/1?lang=en-US
Open in Sumatra PDF and DJVU Reader | Opera forums
Sep 19, 2020 - Here you can post comments about Open in Sumatra PDF and DJVU Reader extension, created by andy-portmen
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https://addons.opera.com/fr/extensions/details/open-in-sumatra-pdf-and-djvu-reader/
Extension Open in Sumatra PDF and DJVU Reader - Add-ons Opera
Adds a context menu item to send PDF links directly to Sumatra PDF
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https://djvu.online/
djvu.online - DJVU online reader
djvuonlinereader