Object Permissions, Can't Find

I'm trying to identify the objects in master that the role public has select permissions on, but when I run this query, I get 4 results where the default schema is null and the major_id column does not correspond to any records in the sys.all_objects table. Where else can I look to find what objects these are. DBO is listed as the grantor.

I appreciate your help.

SELECT *
FROM SYS.DATABASE_PERMISSIONS P,
SYS.DATABASE_PRINCIPALS R
WHERE P.GRANTEE_PRINCIPAL_ID=R.PRINCIPAL_ID and
permission_name='SELECT' and class_desc='OBJECT_OR_COLUMN' and
r.name='public'
order by r.name desc