Package check result: NOTE

Check: CRAN incoming feasibility, Result: NOTE
  Maintainer: ‘Louis Aslett <louis.aslett@durham.ac.uk>’
  
  Found the following (possibly) invalid URLs:
    URL: https://mathgenealogy.org/
      From: DESCRIPTION
            man/get_genealogy.Rd
            man/maths.genealogy-package.Rd
            man/search_id.Rd
            inst/doc/getting-started.html
            README.md
            NEWS.md
      Status: Error
      Message: SSL peer certificate or SSH remote key was not OK [mathgenealogy.org]:
        server verification failed: certificate signer not trusted. (CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none)
    URL: https://mathgenealogy.org/submit.php
      From: man/search_id.Rd
      Status: Error
      Message: SSL peer certificate or SSH remote key was not OK [mathgenealogy.org]:
        server verification failed: certificate signer not trusted. (CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none)
    URL: https://www.mathgenealogy.org/growth_image.php
      From: inst/doc/getting-started.html
      Status: Error
      Message: SSL peer certificate or SSH remote key was not OK [www.mathgenealogy.org]:
        server verification failed: certificate signer not trusted. (CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none)
    URL: https://www.mathgenealogy.org/search.php
      From: inst/doc/getting-started.html
      Status: Error
      Message: SSL peer certificate or SSH remote key was not OK [www.mathgenealogy.org]:
        server verification failed: certificate signer not trusted. (CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none)