What is the abbreviation for Nuveen insured new york tax free new york stock exchange nyse?

Looking for the shorthand of Nuveen insured new york tax free new york stock exchange nyse or how to abbreviate it? We have 2 shorthands for Nuveen insured new york tax free new york stock exchange nyse.

NRK — Nuveen Insured New York Tax-Free (New York Stock Exchange [NYSE])
NXN — Nuveen Insured New York Tax-Free (New York Stock Exchange [NYSE])