<https://www.ghacks.net/2019/10/05/calibre-4-0-e-book-manager-is-out/#webpage>
<http://schema.org/description>
"A new version of the cross-platform e-book manager and reader Calibre was released on October 4, 2019. Calibre 4.0 is a major update that features a completely rewritten e-book viewer among other changes."
<https://www.ghacks.net/2019/10/05/calibre-4-0-e-book-manager-is-out/>