https://aalfons.r-universe.dev/perryhttps://aalfons.r-universe.dev/api/packages/perryhttps://aalfons.r-universe.dev/perry/perry.pdfhttps://aalfons.r-universe.dev/perry/doc/manual.htmlhttps://aalfons.r-universe.dev/perry/NEWShttps://aalfons.r-universe.dev/perry/NEWS.txthttps://aalfons.r-universe.dev/perry/citationhttps://aalfons.r-universe.dev/perry/citation.txthttps://aalfons.r-universe.dev/perry/citation.cff