Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_28235 ( "NSG Nr." real, "Name of the nature reserve" text, "District / Town" text, "Area (ha)" text, "Date established" text )

### Question ###
What Nature reserve number was established on 19961220 20.12.1996

### Accurate SQL ###

SELECT MIN("NSG Nr.") FROM table_28235 WHERE "Date established" = '19961220 20.12.1996'