| Http://: https://medlineplus.gov/genetics/condition/ring-chromosome-20-syndrome/ |
| Http://: https://pubmed.ncbi.nlm.nih.gov/33363513/ |
| Http://: https://medlineplus.gov/genetics/condition/ring-chromosome-20-syndrome/ |
| Http://: https://pubmed.ncbi.nlm.nih.gov/33363513/ |