1. 〈http://tumorsurgery.org/tumor-education/bone-tumors/types-of-bone-tumors/parosteal-osteosarcoma.aspx〉.
2. 〈https://en.wikipedia.org/wiki/Long_bone〉.
3. 〈https://www.hopkinsmedicine.org/health/conditions-and-diseases/sarcoma/bone-sarcomas〉.
4. 〈https://www.hopkinsmedicine.org/health/conditions-and-diseases/sarcoma/osteosarcoma〉.
5. 〈https://www.mayoclinic.org/diseases-conditions/sarcoma/symptoms-causes/syc-20351048〉.