Not a DOI

The resolution service at https://doi.org resolves DOIs. You have attempted to resolve core/services/aop-cambridge-core/content/view/BDC8AE7999DB6E4F234A9098F8927C84/S136898000400117Xa.pdf/food-youth-and-the-mediterranean-diet-in-spain-development-of-kidmed-mediterranean-diet-quality-index-in-children-and-adolescents.pdf, which is not a DOI.

core/services/aop-cambridge-core/content/view/BDC8AE7999DB6E4F234A9098F8927C84/S136898000400117Xa.pdf/food-youth-and-the-mediterranean-diet-in-spain-development-of-kidmed-mediterranean-diet-quality-index-in-children-and-adolescents.pdf may be a Handle (DOIs are a special sort of Handle). If core/services/aop-cambridge-core/content/view/BDC8AE7999DB6E4F234A9098F8927C84/S136898000400117Xa.pdf/food-youth-and-the-mediterranean-diet-in-spain-development-of-kidmed-mediterranean-diet-quality-index-in-children-and-adolescents.pdf is a valid Handle you should be able to resolve it at https://hdl.handle.net.