Nickles were propaganda leaflets. They were dropped in containers which burst open in the air and spread the leaflets over a large area. The numbers refer to which series of leaflets that were dropped, G.89 and G.83 and how many "bombs" were dropped 3 of one type and 2 of the other.
There are examples of these on this site:
http://www.psywar.org/
If you enter the codes G.83 or G.89 on this page:
http://www.psywar.org/leaflets.php
you can see what they may have looked like (assuming the year is correct).