Bibliography (7):

1. Crows Perform Yet Another Skill Once Thought Distinctively Human: Scientists demonstrate that crows are capable of recursion—a key feature in grammar. Not everyone is convinced

2. Recursive sequence generation in monkeys, children, US adults, and native Amazonians

3. Ravens parallel great apes in physical and social cognitive skills

4. Modifications to the Aesop’s Fable Paradigm Change New Caledonian Crow Performances

5. Birds do have a brain cortex—and think: Like mammals, birds have a pallium that sustains correlates of consciousness

6. Wikipedia Bibliography:

   1. Center embedding

   2. https://en.wikipedia.org/wiki/Macaque  :

      https://en.wikipedia.org/wiki/Macaque