https://elipousson.r-universe.dev/sfexthttps://elipousson.r-universe.dev/api/packages/sfexthttps://elipousson.r-universe.dev/sfext/sfext.pdfhttps://elipousson.r-universe.dev/sfext/doc/manual.htmlhttps://elipousson.r-universe.dev/sfext/NEWShttps://elipousson.r-universe.dev/sfext/NEWS.txthttps://elipousson.r-universe.dev/sfext/citationhttps://elipousson.r-universe.dev/sfext/citation.txthttps://elipousson.r-universe.dev/sfext/citation.cff