Man pages matching name helpviewer in section 1:

HelpViewer.1.en	debian 10 / helpviewer.app
HelpViewer.1.en	debian 11 / helpviewer.app
helpviewer.1.en	debian 11 / wxpython-tools
HelpViewer.1.en	debian 12 / helpviewer.app
helpviewer.1.en	debian 12 / wxpython-tools