https://stla.r-universe.dev/freewallhttps://stla.r-universe.dev/api/packages/freewallhttps://stla.r-universe.dev/freewall/freewall.pdfhttps://stla.r-universe.dev/freewall/doc/manual.htmlhttps://stla.r-universe.dev/freewall/citationhttps://stla.r-universe.dev/freewall/citation.txthttps://stla.r-universe.dev/freewall/citation.cff