https://youyifong.r-universe.dev/copcorhttps://youyifong.r-universe.dev/api/packages/copcorhttps://youyifong.r-universe.dev/copcor/copcor.pdfhttps://youyifong.r-universe.dev/copcor/doc/manual.htmlhttps://youyifong.r-universe.dev/copcor/citationhttps://youyifong.r-universe.dev/copcor/citation.txthttps://youyifong.r-universe.dev/copcor/citation.cffhttps://youyifong.r-universe.dev/copcor/doc/copcor-vignette.pdf.asishttps://youyifong.r-universe.dev/articles/copcor/copcor-vignette.pdf