select 
  sum(digital) as "digital", sum(hardcopy) as "hardcopy", sum(total) as "total"
from (
  select
    distinct re.reference_id,
    min(re.time_stamp),
    case when form_number is null and re.state_=1 then 1 else 0 end as digital,
    case when form_number is not null and re.state_=1 then 1 else 0 end as hardcopy,
    case when re.state_=1 then 1 else 0 end as total
  from
    Reference r
    join Reference_Events re on r.id=re.reference_id
  where
    re.time_stamp>=to_timestamp('01.09.2013 00:00:00','DD.MM.YYYY HH24:MI:SS')
    and trunc(re.time_stamp, 'DD')<=to_date('30.09.2013 23:59:59','DD.MM.YYYY HH24:MI:SS') 
    
  group by re.time_stamp, re.state_, form_number, re.reference_id
)