https://mikewlcheung.r-universe.dev/symSEMhttps://mikewlcheung.r-universe.dev/api/packages/symSEMhttps://mikewlcheung.r-universe.dev/symSEM/symSEM.pdfhttps://mikewlcheung.r-universe.dev/symSEM/doc/manual.htmlhttps://mikewlcheung.r-universe.dev/symSEM/NEWShttps://mikewlcheung.r-universe.dev/symSEM/NEWS.txthttps://mikewlcheung.r-universe.dev/symSEM/citationhttps://mikewlcheung.r-universe.dev/symSEM/citation.txthttps://mikewlcheung.r-universe.dev/symSEM/citation.cff