Okular - image, ebook, pdf reader - The Portable Freeware Collection Forums
PDF annotation interoperability with other apps · Issue #2486 · xournalpp/xournalpp · GitHub
Telegram: usar el visor de PDF predeterminado en KDE Plasma. - Milanga Electrónica
Request for preview of highlights/notes in annotations tab of okular that is a bit more expressive then just generic text "highlight", a bit like zotero guyz are doing it : r/kde
linux - Customise Okular to modify highlight tool properties - Super User