https://alfcano.r-universe.dev/rk.gratefulhttps://alfcano.r-universe.dev/api/packages/rk.gratefulhttps://alfcano.r-universe.dev/rk.grateful/rk.grateful.pdfhttps://alfcano.r-universe.dev/rk.grateful/doc/manual.htmlhttps://alfcano.r-universe.dev/rk.grateful/citationhttps://alfcano.r-universe.dev/rk.grateful/citation.txthttps://alfcano.r-universe.dev/rk.grateful/citation.cff