Source Serif 4 / 400
{
  "copyright": {
    "en": "© 2014 - 2021 Adobe Systems Incorporated (http://www.adobe.com/), with Reserved Font Name ‘Source’."
  },
  "licenseURL": {
    "en": "http://scripts.sil.org/OFL"
  }
}

Source Serif 4 / 600
{
  "copyright": {
    "en": "© 2014 - 2021 Adobe Systems Incorporated (http://www.adobe.com/), with Reserved Font Name ‘Source’."
  },
  "licenseURL": {
    "en": "http://scripts.sil.org/OFL"
  }
}

Source Serif 4 / 700
{
  "copyright": {
    "en": "© 2014 - 2021 Adobe Systems Incorporated (http://www.adobe.com/), with Reserved Font Name ‘Source’."
  },
  "licenseURL": {
    "en": "http://scripts.sil.org/OFL"
  }
}