Hierarchical structure

Hi, I need to create a view using hierarchical structure.
Let me explain how is designed the table and what's the expected result.

TABLE:
coo_nro integer
coo_nro_father integer
level integer


DATA:
100 – null – 1
106 – null – 1
134 – 100 – 2
725 – 100 – 2
635 – 106 – 2
423 – 134 – 3
814 – 725 – 3


EXPECTED RESULT:
100 - 1
134 – 2
423 – 3
725 – 2
814 – 3
106 – 1
635 – 2
. . . so on

Basically, my result should be this way, not necessary spaces, but
sorted by hierarchic.

Is this possible on Postgres?
Could you help me?



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