https://flying-sheep.r-universe.dev/knn.covertreehttps://flying-sheep.r-universe.dev/api/packages/knn.covertreehttps://flying-sheep.r-universe.dev/knn.covertree/knn.covertree.pdfhttps://flying-sheep.r-universe.dev/knn.covertree/doc/manual.htmlhttps://flying-sheep.r-universe.dev/knn.covertree/citationhttps://flying-sheep.r-universe.dev/knn.covertree/citation.txthttps://flying-sheep.r-universe.dev/knn.covertree/citation.cff