https://matthewabirk.r-universe.dev/birkhttps://matthewabirk.r-universe.dev/api/packages/birkhttps://matthewabirk.r-universe.dev/birk/birk.pdfhttps://matthewabirk.r-universe.dev/birk/doc/manual.htmlhttps://matthewabirk.r-universe.dev/birk/NEWShttps://matthewabirk.r-universe.dev/birk/NEWS.txthttps://matthewabirk.r-universe.dev/birk/citationhttps://matthewabirk.r-universe.dev/birk/citation.txthttps://matthewabirk.r-universe.dev/birk/citation.cff